Seid_Sitotaw_March_2019_Final_Thesis.pdf

DSpace Institution
DSpace Repository http://dspace.org
Hydraulic engineering Thesis
2020-03-15
ASSESSMENT OF DRINKING WATER
QUALITY FROM SOURCE TO POINT
OF CUSTOMER TAPS: THE CASE OF
GONDAR TOWN.
SITOTAW, SEID
http://hdl.handle.net/123456789/10318
Downloaded from DSpace Repository, DSpace Institution's institutional repository

BAHIR DAR UNIVERSITY
BAHIR DAR INSTITUTE OF TECHNOLOGY
SCHOOL OF RESEARCH AND GRADUATE STUDIES
FACULTY OF CIVIL AND WATER RESOURCES ENGINEERING
ASSESSMENT OF DRINKING WATER QUALITY FROM
SOURCE TO POINT OF CUSTOMER TAPS: THE CASE OF
GONDAR TOWN.
SEID SITOTAW BIRKU
BAHIR DAR, ETHIOPIA
March 22, 2019

ASSESSMENT OF DRINKING WATER QUALITY FROM SOURCE
TO POINT OF CUSTOMER TAPS: THE CASE OF GONDAR TOWN.
SEID SITOTAW BIRKU
A thesis submitted to the School of Research and Graduate Studies of Bahir Dar
Institute of Technology, BDU in partial fulfillment of the requirements for the degree
of
Master of Science in Engineering Hydrology
in the Faculty of Civil and Water Resources Engineering.
Advisor Name: Dr Ing. Mulugeta Azeze Belete
Co-Advisor Name: Tadesual Asamin Setargie (M.Sc.)
Bahir Dar, Ethiopia
March 22, 2019

i
DECLARATION
I, the undersigned, declare that the thesis comprises my own work. In compliance
with internationally accepted practices, I have acknowledged and refereed all
materials used in this work. I understand that non-adherence to the principles of
academic honesty and integrity, misrepresentation/ fabrication of any
idea/data/fact/source will constitute sufficient ground for disciplinary action by the
University and can evoke penal action from the sources, which have not been
properly cited or acknowledged.

ii
© 2019
Seid Sitotaw Birku
ALL RIGHTS RESERVED

iii
Bahir Dar University
Bahir Dar Institute of Technology
School of Research and Graduate Studies
Faculty of Civil and Water Resources Engineering
THESIS APPROVAL SHEET
Student:

iv
Dedicated to my momHalima Yibre.
(I will always remember love in my life.)

v
ACKNOWLEDGEMENT
First, I would like to thank the God for his invaluable supporting and guidance in all
aspects of my life. Next, I would like to express my sincere thanks to my advisor Dr.Ing
Mulugeta Azeze (Faculty of Civil and Water Resources Engineering,Bahir Dar Institute
of Technology) for his invaluable and tireless efforts in supporting, and advising me on
this thesis study. Thank you for your timely supervising and sharing your valuable
professional experiences to equip me in the areas of investigation of drinking water
quality from source to point of distribution. I have also benefited a lot from Gondar
Water and Sewerage Office Laboratory; therefore, it gives me great pleasure to express
my great gratitude to the personnel for their willingness to use all the equipment and
reagents without any payment. I also thank all my friends and relatives who in one way
or another supported me during the whole length of my thesis study

vi
LIST OF ABBREVIATIONS
APHA American Public Health Association
AWTP Angereb Water Treatment Plant
ANOVA Analysis of Variance
BH Borehole
CFU Colony Forming Unit
DPD Diethyl-Phenylene-Diamine
EC Electric Conductivity
ES Ethiopian Standard
FC Fecal Coliform
NTU Ne photometric Turbidity Unit
RFC Residual Free Chlorine
TDS Total dissolved solids
GTP Growth and Transformation Program
HH Households
NTU Nepholometeric Turbidity Unit
TC Total Coliform
WHO World Health Organization
UNICEF United Nations Children's Fund

vii
TABLE OF CONTENTS
Contents Page
DECLARATION _____________________________________________________ i
THESIS APPROVAL SHEET __________________________________________ iii
ACKNOWLEDGEMENT ______________________________________________v
LIST OF ABBREVIATIONS___________________________________________ vi
TABLE OF CONTENTS ______________________________________________vii
LIST OF FIGURES ___________________________________________________x
LIST OF TABLES ___________________________________________________xii
LIST OF APPENDIX FIGURES _______________________________________ xiii
LIST OF APPENDIX TABLES ________________________________________ xiv
ABSTRACT _______________________________________________________ xvi
1.INTRODUCTION ___________________________________________________1
1.1. Background __________________________________________________1
1.2. Statement of the Problem________________________________________3
1.3. Objectives of the Study _________________________________________4
1.3.1. General Objective __________________________________________4
1.3.2. Specific Objectives _________________________________________4
1.4. Scope of the Study _____________________________________________4
1.5. Significance of the Study ________________________________________4
2.LITERATURE REVIEW _____________________________________________6
2.1. Human Health and Water Quality _________________________________6
2.2. Performance Evaluation of Drinking Water Treatment Plant ____________8
2.3. Factors affecting Water Quality at Distribution Systems________________9
2.4. Physicochemical Quality Parameters of Drinking Water ______________10
2.4.1. PH _____________________________________________________10
2.4.2. Temperature _____________________________________________10
2.4.3. Turbidity ________________________________________________11
2.4.4. Electrical Conductivity _____________________________________11
2.4.5. Total Dissolved Solid ______________________________________12
2.4.6. Dissolved Oxygen_________________________________________12
2.4.7. Free Residual Chlorine _____________________________________13

viii
2.4.8. Nitrate and Nitrite _________________________________________13
2.4.9. Ammonia________________________________________________14
2.4.10. Phosphate _______________________________________________14
2.4.11. Iron ____________________________________________________15
2.5. Bacteriological Water Quality Parameters of Drinking Water __________15
2.5.1. Coliform Bacteria _________________________________________16
2.5.2. FecalColiforms (Thermo tolerant Bacteria) _____________________17
2.6. WHO and Ethiopian Standards of Drinking Water quality _____________18
3.MATTERIALS AND METHODS _____________________________________20
3.1. Research Design______________________________________________20
3.2. Description of the Study Area ___________________________________20
3.3. Water Supply and Sanitation ____________________________________22
3.4. Pressure Zones in Distribution Systems____________________________24
3.5. Existing Angereb Water Treatment Plant __________________________26
3.6. Materials____________________________________________________30
3.6.1. Source of Data____________________________________________30
3.6.2. Sample Size and Sampling Points_____________________________30
3.6.3. Equipment and Reagents____________________________________33
3.7. Methods ____________________________________________________35
3.7.1. Data Collection ___________________________________________35
3.7.2. Data Analyses ____________________________________________36
3.7.2.1. Physiochemical Analyses ___________________________________36
3.7.2.2. Bacteriological Analyses ___________________________________37
3.8. Statistical Application _________________________________________38
4.RESULTS AND DISCUSION ________________________________________39
4.1. Temporal Variation of Water Quality Parameters at DDifferent Sampling
Sites 39
4.1.1. Total Coliform (TC) _______________________________________41
4.1.2. Fecal Coliform (FC) _______________________________________42
4.1.3. PH _____________________________________________________44
4.1.4. Temperature _____________________________________________45
4.1.5. Turbidity ________________________________________________47
4.1.6. Electrical Conductivity (EC)_________________________________49
4.1.7. Total Dissolved Solid (TDS) ________________________________51

ix
4.1.8. Dissolved Oxygen (DO) ____________________________________52
4.1.9. Free Chlorine Residual _____________________________________53
4.1.10. Phosphate (PO4
3-
) _________________________________________55
4.1.11. Nitrate (NO3
-
) and Nitrite (NO2)______________________________55
4.1.12 Iron (Fe) __________________________________________________58
4.1.13 Ammonia _________________________________________________59
4.2. Spatial Variation of Water Quality at All Sampling Sites ______________61
4.2.1. PH _____________________________________________________61
4.2.2. Temperature _____________________________________________61
4.2.3. Turbidity ________________________________________________62
4.2.4. TDS____________________________________________________63
4.2.5. Electric conductivity (EC) __________________________________64
4.2.6. Dissolved Oxygen_________________________________________64
4.2.7. Nitrate and Nitrite _________________________________________65
4.2.8. Phosphate _______________________________________________66
4.2.9. Ammonia________________________________________________67
4.2.10. Free Residual Chlorine _____________________________________67
4.2.11. TC and FC_______________________________________________68
4.3. Performance Evaluation of Angereb Treatment Plant _________________70
4.3.1. Turbidity from raw to potable water___________________________70
5.CONCLUSION AND RECOMMENDATIONS __________________________72
5.1. Conclusion __________________________________________________72
5.2. Recommendations ____________________________________________73
REFERENCES ______________________________________________________74
APPENDIX_________________________________________________________80
Appendix A: List of Figures __________________________________________80
Appendix B: List of Tables___________________________________________84
Appendix C: Reports_______________________________________________106

x
LIST OF FIGURES
Figure 3-1: Location map of Gondar town. .................................................................22
Figure 3-2: Map showing pressure zones and reservoir cover areas ...........................25
Figure 3-3: Chemical preparation tanks and control panel in the chemical building ..26
Figure 3-4: Rapid mixing chamber and chemical dosing arrangement .......................27
Figure 3-5: Picture of baffled flocculation tanks .........................................................28
Figure 3-6: Rapid Sand clarifiers.................................................................................28
Figure 3-7: Angereb Water Treatment Plant layout and scheme.................................29
Figure 3-8: Components of Angereb Water Treatment Plant......................................29
Figure 3-9: Location of sampling sites in Gondar town ..............................................33
Figure 3-10: Some equipment used in the field and laboratory Study ........................34
Figure 3-11: Research methodology process diagram.................................................35
Figure 4-1: Total coliform measurement at different months with different water
sources..........................................................................................................................41
Figure 4-2: Total coliform measurement at different months on tap users..................42
Figure 4-3: Fecal coliform measurement at different months with different water
sources..........................................................................................................................43
Figure 4-4: Fecal coliform measurement at different months on tap users .................43
Figure 4-5: PH measurement at different months with different water sources..........45
Figure 4-6: PH measurement at different months on tap users....................................45
Figure 4-7: Temperature at different water sources with WHO..................................46
Figure 4-8: temperature measurement at different months on tap users......................47
Figure 4-9: turbidity measurement at different months with different water sources .48
Figure 4-10: Turbidity measurement at different months on tap users........................49
Figure 4-11: EC measurement at different months with different water sources........50
Figure 4-12: EC measurement at different months on tap users..................................51
Figure 4-13: TDS measurement at different months with different water sources......51
Figure 4-14: TDS measurement at different months on tap users ...............................52
Figure 4-15: DO measurement at different months with different water sources .......53
Figure 4-16: DO measurement at different months on tap users.................................53
Figure 4-17: FRC measurement at different months with different water sources......54
Figure 4-18: FRC measurement at different months on tap users ...............................54

xi
Figure 4-19: Phosphate measurement at different months with different water sources.
......................................................................................................................................55
Figure 4-20: Nitrate measurement at different months with different water sources..56
Figure 4-21: Nitrate measurement at different months on tap users............................57
Figure 4-22: Nitrite Concentration during Wet and Dry Season as Compared to
Maximum Permissible Limit .......................................................................................58
Figure 4-23: Iron Concentration during Wet and Dry Season as Compared to Maximum
Permissible Limit.........................................................................................................59
Figure 4-24: Ammonia Concentration during Wet and Dry Season as Compared to
Maximum Permissible Limit .......................................................................................59
Figure 4-25: PH variation from sources to Pressure zones..........................................61
Figure 4-26: Temperature variation from sources to pressure zones...........................62
Figure 4-27: Turbidity variation from sources to pressure zones................................63
Figure 4-28: TDS variation from sources to pressure zones........................................63
Figure 4-29: EC variation from sources to pressure zones..........................................64
Figure 4-30: DO variation from sources to pressure zones .........................................65
Figure 4-31: Nitrate variation from sources to pressure zones....................................65
Figure 4-32: Nitrite variation from sources to pressure zones.....................................66
Figure 4-33: Phosphate variation from sources to pressure zones...............................67
Figure 4-34: Ammonia variation from sources to pressure zones ...............................67
Figure 4-35: Free residual Chlorine variation from sources to pressure zones ...........68
Figure 4-36: TC and FC from sources to pressure zones.............................................69
Figure 4-37: Clarified turbidity performance. .............................................................70
Figure 4-38: filtered water turbidity measurements from the treatment plant.............71

xii
LIST OF TABLES
Table 2-1: The WHO guideline values of drinking water quality parameters.............19
Table 3-1: Existing Water Supply Sources..................................................................23
Table 3-2: Water reservoirs (GTWSSO, 2017) ...........................................................26
Table 3-3: Number of sampling site with its pressure zone location...........................32
Table 4-1: Drinking water quality compliance with the WHO permissible limits in the
dry seasons (Oct-May) and wet seasons (Jun-Sep) in Treated Angereb reservoir,
Kolladeba Reservoir, spring and Tap users Average pressure zones. .........................40
Table 4-2: Correlations between water quality parameters. ........................................60
Table 4-4: Raw and treated water turbidities, removal efficiency of AWTP and
compliance with WHO standards ................................................................................70

xiii
LIST OF APPENDIX FIGURES
Appendix Figure 1: Measurement of PH at different sampling sites...........................80
Appendix Figure 2: Measurement of Temperature at different sampling sites ...........80
Appendix Figure 3: Measurement of Turbidity at different sampling sites.................80
Appendix Figure 4: Measurement of TDS at different sampling sites ........................81
Appendix Figure 5: Measurement of TDS at different sampling sites ........................81
Appendix Figure 6: Measurement of DO at different sampling sites..........................81
Appendix Figure 7: Measurement of TC and FC at different sampling sites..............82
Appendix Figure 8: Measurement of Iron at different sampling sites.........................82
Appendix Figure 9: Measurement of FRC at different sampling sites ........................82
Appendix Figure 10: Measurement of Phosphate at different sampling sites .............83
Appendix Figure 11: Measurement of Nitrate at different sampling sites...................83
Appendix Figure 12: Measurement of Ammonia at different sampling sites..............83

xiv
LIST OF APPENDIX TABLES
Appendix Table 1: Analysis of variance for PH..........................................................84
Appendix Table 2: Analysis of variance for Temperature...........................................84
Appendix Table 3: Analysis of variance for Turbidity................................................84
Appendix Table 4: Analysis of variance for electric conductivity. .............................84
Appendix Table 5: Analysis of variance for TDS. ......................................................84
Appendix Table 6: Analysis of variance for Dissolved Oxygen .................................85
Appendix Table 7: Analysis of variance for Total Coliform.......................................85
Appendix Table 8: Analysis of variance for Fecal Coliform.......................................85
Appendix Table 9: Analysis of variance for Iron. .......................................................85
Appendix Table 10: Analysis of variance for FRC. ....................................................85
Appendix Table 11: Analysis of variance for Phosphate.............................................85
Appendix Table 12: Analysis of variance for Nitrate..................................................86
Appendix Table 13: Analysis of variance for Nitrite...................................................86
Appendix Table 14: Analysis of variance for Ammonia.............................................86
Appendix Table 15: Analysis of variance for PH at treated different source..............86
Appendix Table 16: Analysis of variance for Temperature at treated different source.
......................................................................................................................................86
Appendix Table 17: Analysis of variance for Turbidity at treated different source....86
Appendix Table 18: Analysis of variance for EC at treated different source..............87
Appendix Table 19: Analysis of variance for TDS at treated different source. ..........87
Appendix Table 20: Analysis of variance for Dissolved Oxygen at treated different
source...........................................................................................................................87
Appendix Table 21: Analysis of variance for Total Coliform.....................................87
Appendix Table 22: Analysis of variance for Fecal Coliform at treated different source.
......................................................................................................................................87
Appendix Table 23: Analysis of variance for Iron at treated different source. ...........87
Appendix Table 24: Analysis of variance for FRC at treated different source. ..........88
Appendix Table 25: Analysis of variance for Phosphate at treated different source...88
Appendix Table 26: Analysis of variance for Nitrate at treated different source........88
Appendix Table 27: Analysis of variance for Nitrite at treated different source.........88
Appendix Table 28: Analysis of variance for Ammonia at treated different source...88
Appendix Table 29: PH sample detail measurement...................................................89

xv
Appendix Table 30: Temperature Sample detail measurement...................................90
Appendix Table 31: Turbidity sample detail measurement.........................................91
Appendix Table 32: Electric Conductivity detail measurement..................................92
Appendix Table 33: Total Dissolved Solids detail measurement................................93
Appendix Table 34: Dissolved Oxygen sample detail.................................................94
Appendix Table 35: Total Coliform sample detail. .....................................................95
Appendix Table 36: Fecal Coliform sample detail......................................................96
Appendix Table 37: Iron sample detail........................................................................97
Appendix Table 38: Free Residual Chlorine sample detail. ........................................98
Appendix Table 39: Phosphate Sample detail. ............................................................99
Appendix Table 40: Nitrate sample detail. ..................................................................99
Appendix Table 41: Nitrite sample detail..................................................................101
Appendix Table 42: Ammonia sample detail. ...........................................................102
Appendix Table 43: Average measurement of parameters seasonally. .....................103
Appendix Table 44: Average measurement of parameters at different location. ......104

xvi
ABSTRACT
The spatial and temporal variations of physical, chemical and biological water quality
parameters were used to assess the quality of drinking water in Gondar town and
evaluate the performance of its treatment plant. The town gets its water supply from
Angereb reservoir, Kolladeba boreholes, and from four springs situated around the
town. Water samples were collected on a monthly basis from all the sources and from
32 tap users at nine pressure zones in the distribution systems.
The collected samples examined in a laboratory for physiochemical and bacteriological
analyses. Thirty-five sampling sites were chosen along the watercourse. To characterize
the water quality, was examined using 14 water quality parameters:- water temperature,
electrical conductivity, turbidity, PH, total dissolved solids, nitrate(NO3
-
), nitrite(NO2),
phosphate(PO4
3-
), ammonia(NH3) iron (Fe), dissolved oxygen, free residual chlorine,
total coli form and fecal coli form. All the water quality parameters at all water sources
significantly vary (p<0.05). Most of the water quality parameters at distribution
systems significantly vary (p<0.05) at the tap customers along the pipelines in the
distribution systems except PH. The water quality also showed higher values of the
examined parameters in the rainy season than the dry season in the year 2017/18. All
water quality parameters at all water sources were within the WHO guideline except
the temperature, phosphate, total coliform, fecal coliform, and free residual chlorine
parameters. All parameters showed increment in concentration from water sources to
distribution system both in wet and dry season. Therefore, it can be concluded that along
distribution system, the drinking water is prone to contamination and the water quality
decline along distribution system.
Comparison of the results with WHO and the Ethiopian drinking water quality
standards indicated that the raw water from Angereb is of poor quality, while the treated
water is satisfactory. Therefore, the performance of the Angereb treatment plant was in
good condition with turbidity removal efficiency of 99.66%.
Key Words: Drinking water quality parameters, performance of treatment plant,
WHO standard, household tap, distribution system

Assessment of Drinking Water Quality from treated source to customer taps: The case
. of Gondar Town .
Bahir Dar Institute of Technology (BiT)
1
1. INTRODUCTION
1.1. Background
Water is one of the main important components of the environment. Water is essential
for life, but it can and does transmit disease in countries in all continents from the
poorest to the wealthiest without water life on earth would not exist. Water used for
domestic consumptions, agricultural and industrial productions and processes,
recreation and power production etc. The domestic consumption includes. Water used
for drinking, cooking, and preparation of food, bathing, cleaning, washing and personal
hygiene, watering in gardens, and water for livestock, sanitation. Usually such water
should be clear and aesthetically attractive, low turbidity and color recommended
(5NTU and 15TCU) respectively, by World Health Organization (WHO,2011)
guidelines and should not be saline, contain any compounds that cause aggressive and
taste, should not cause corrosion scale formation, discoloring or staining and should not
have at temperature unsuitable for consumption.
Water quality is denied by a collection of upper and lower limits on selected possible
contaminants in water. This is evaluated by using water quality indicators, which can
be physical, chemical and biological. Within each class, a number of quality variables
are considered. The magnitude of these indicators can affect the acceptability of water
quality for its intended use and is often governed by regulations. Water is known as the
“universal solvent” because it has the ability to dissolve solids and absorb gases and
other liquids. Because of this solvent power, all natural water contains minerals and
other substances in solution, which have been picked up from the air, the soil, and rocks
through and over which it passes (Minwuye, 2015).
Water derived from the resources may not necessarily pure since it contains dissolved
inorganic and organic substances, living organisms such as viruses and bacteria. For
this reason, according to (Amenu et al, 2014) guidelines water intended for domestic
uses should be free from toxic substances and microorganisms that have health
significance (Amenu et al, 2014).
Although water is essential for life, it can and does transmit diseases. The most
predominant waterborne disease, diarrhea, has an estimated annual incidence of 4.6

. of Gondar Town .
2
billion episodes and causes 2.2 million deaths every year (UNICEF, 2012). Access to
safe drinking water and sanitation is a global concern. However, developing countries
like Ethiopia have suffered from a lack of access to safe drinking water quality and
cause of human health problems due to waterborne diseases. Today, close to a billion
people, most living in the developing world, do not have access to safe and adequate
water (UNICEF, 2012).
One of the most important factors that affect drinking water quality through distribution
and with sustainable use of town water supply systems is the quality of water, the
distribution systems to users (Brikké, 2000). If domestic water supply of any town
failed to meet acceptable drinking water quality standards (that is; physical, chemical,
and bacteriological), people may stop using the water and resort to unsafe sources and
was further exposed to acute and chronic illnesses (Karn, 2002) there are several
variants of the fecal–oral pathway of waterborne is ease transmission. These include
contamination of drinking water catchments (e.g. by human or animal faces), water
within the distribution system (e.g. through leaky pipes or outdated infrastructure) of
stored household water as result of unhygienic handling. Millions of people are exposed
to unsafe levels of chemical contaminants in their drinking water. This may be due to a
lack of proper management of urban and industrial wastewater or agricultural run-off
water potentially giving rise to long-term exposure to pollutants, which can have
arranged of serious health implications.
Acceptable quality shows the safety of drinking water in terms of its physical, chemical
and bacteriological parameters (WHO, 2011) User “perceptions of quality also carry
great weight in their drinking water safety”(França Doria, 2010).
The existing drinking water system of the Gondar town designed from Angereb dam
and boreholes, Kolladeba deep wells, and springs. It is critical to identify whether the
water obtained from the sources, along with its various stages until it reaches the
consumers, is safe with regard to water quality parameters. Therefore, this study effort
to assess the drinking water quality from the main existing drinking water system of
Gondar town in terms of water quality parameters such as physiochemical,
bacteriological and pollution loads at the sourceand tap users. According to Water, bore
diseases recorded for the past six years (2010-2017) the data from Gondar Town health

. of Gondar Town .
3
Office the infected people were 43,910 in seven years (office report, 2017). Therefore,
the waterborne diseases and water-related diseases are problems of Gondar Water
quality.
The results of this study are useful to address the main cause of public health problems
related to the deteriorated quality of drinking waterand to evaluate the status of the
existing treatment plant comparison of the water quality results with the WHO
standards.
1.2. Statement of the Problem
In many countries, water quality deterioration in water supply distribution systemsis a
big issue; which might be a result of many interconnected physical, chemical, and
biological factors. Water quality deterioration and water-related diseases resultin
serious public health concerns in many developing countries like Ethiopia. Lack of safe
water and the risk of waterborne diseases are serious health-related problems in
Ethiopia (Gebissa, 2016). Gondar town is mainly suffering from waterborne diseases,
especially in diarrhea and typhoid fever,due to poor drinking water quality.
Contamination of water may not be at the source but it may also happen after leaving
the source, on the distribution system from source to consumer’s taps. Most of the time
communities give attentions mainly for water supply not for its quality.The reports also
showed that water sources and distribution systems of towns and rural communities
alike have serious water quality problems. Assessment of bacteriological and
physiochemical qualities of urban source water and tap water distribution systems in
Akaki-Kalit sub-city of Addis Ababa (Mengestayehu,2007), Ziway town (Kassahun,
2008), Bahir Dar city (Getnet,2008), and Adama town (Temesgen, 2009) showed
contaminations of water by indicator bacteria such as total coliforms, fecal coliforms.
Systems that have large transmission and distribution lines may have a problem on
changes of pressure in the distribution system. For the reason that the increase in water
age is dependent on the difference between the production and consumption rates, a
high residence time in pipes and storage duration in water tanks are some of the
problems. Therefore, the objective of this study was to assess the physiochemical and
bacteriological quality of water after treatment to consumers’ taps.

. of Gondar Town .
4
1.3. Objectives of the Study
1.3.1. General Objective
The main objective of this study is to assess the suitability of Gondar town drinking
water quality from the treated source to consumer’s taps.
1.3.2. Specific Objectives
The research has the following specific objectives;
 Characterize the Gondar town drinking water with selected physiochemical and
biological water quality parameters,
 Evaluate the spatial-temporal variations of drinking water quality,
 Assess whether the observed physiochemical and biological water quality results
are within WHO and Ethiopian standards, and
 Evaluate the performance of Gondar town drinking water treatment plant.
1.4. Scope of the Study
This study specifically focused on the assessment of factors that affect the potable water
quality of water supply schemes in Gondar town. Due to financial limitation, the water
quality work assessed in this study is limited to the selected microbial, physical and
chemical water quality parameters. Moreover, the water samples taken were limited in
number, space and time. The one-year monthly data has been collected from all water
sources and 32 sampled tap users from nine pressure zone and 5 years recorded data
used for the performance evaluation of the Angereb treatment plant.
In this study, physiochemical parameters; like turbidity, potential of Hydrogen (PH),
electric conductivity (EC), total dissolved solids (TDS), water temperature, RFC,
Nitrate (NO3
-
), Nitrite, Iron, Ammonia, Phosphate(PO4
3-
) and bacteriological
parameters like Fecal Coliform (FC)and Total Coliform (TC) bacteria were involved.
The study tried to identify which water quality parameter, at what time and location,
show a significant variation by comparing with WHO and Ethiopian standards.
1.5. Significance of the Study
The outcome of this study point out the possible sources of pollution responsible for
the observed water quality problem. Safe drinking water is an essential component of

. of Gondar Town .
5
primary health care and is vital for poverty alleviation. Introducing improved water
supply sources at the household level to enhance personal and community awareness.
Assessment, under this study, indicated the temporal and spatial variation of
physiochemical and bacteriological parameters from source (i.e. Angereb and
Kolladeba reservoirs and springs) to tap users including pressure zones in the
distribution systems. The study would aim to update the drinking water quality status
of the study area by assessing and evaluating basic parameters of water and compare
with WHO and Ethiopian standards. Since there is no enough document or research
related to this title in the study area, this study would be use as initial document for
other works. The study might also be used for as an input to identify more detected
areas and that helps for researchers and policy makers, Environment al scientists, any
concerned persons and other stakeholders to implement proper disinfection time,
sufficient dosage and as up dated water quality conditions of the Gondar Town Water
Supply system. The concluded result based on one-year monthly collected data may not
fully represent the water quality of Gondar town before or after the year of collection
2009. Similarly, the result may not directly be used to assess the water quality of nearby
towns.

. of Gondar Town .
6
2. LITERATURE REVIEW
2.1. Human Health and Water Quality
Water quality refers to the physical, chemical and biological characteristics of water. It
is a measure of the condition of water relative to the requirements of one or more biotic
species and or to any human need or purpose. It is most frequently used by reference to
a set of standards against which compliance can be assessed(WHO, 2011).
To be safe for human consumption, drinking water must be free from microorganisms
capable of causing disease. It must not contain minerals and organic substances at
concentrations that could produce adverse effects. Drinking water should be
aesthetically acceptable; it should be free from apparent turbidity, color, and odor, and
from any objectionable taste(WHO, 2011).
The water quality of urban drinking water should satisfy standards set by WHO (world
health organization) and national standards. Water quality test conducted for different
water quality parameters such as turbidity, coliform, residual Chlorine, PH etc. Water
quality mainly related to drinking water, hygiene, sanitation, and human health. The
World Health Organization estimated that up to 80% of all sicknesses and diseases in
the world caused by inadequate sanitation, polluted water or unavailability of water.
Approximately three out of five persons in developing countries do not have access to
safe drinking water and only about one in four has any kind of sanitary facilities.
The transmission of diarrheal and water-related diseases are directly linked to
inadequate access to water and hygienic practices. Diseases transmitted from the host
through water, food and direct contact with human waste contamination by sewage or
human excrement presents the greatest danger to public health associated with drinking
water. Bacteriological testing continues to provide the most sensitive means for the
detection of such pollution.
Livestock, poultry, and industrial operations have properties that can generate large
amounts of manure and waste. Consequently, diseases will continue to spread among
the poor until adequate wastewater disposal accompanies the provision of safe drinking
water. Drinking water quality has a strong impact on people’s health because water is

. of Gondar Town .
7
a vehicle of transmission for many pathogenic microorganisms that cause diarrhea
diseases (Howard, 2010).
Access to safe drinking water and sanitation is a global concern. However, developing
countries, like Ethiopia, have suffered from a lack of access to safe drinking water from
improved sources and to adequate sanitation services (WHO, 2004). As a result, people
are still dependent on unprotected water sources such as rivers, streams, springs, and
hand dug wells. Since these sources are open, they are highly susceptible to flood and
birds, animals, and human contamination. In addition, most sources are found near
gullies where open field defecation is common and flood-washed wastes affect the
quality of water.
Ethiopia is one of the countries in the world with the worst of all water quality problems.
It has the lowest water supply and sanitation coverage in Sub-Saharan countries with
only 42% and 28% for water supply and sanitation, respectively (Federal Democratic
Republic Ethiopian Urban water supply and sanitation project, 2007). Most of the
population of Ethiopia does not have access to safe and reliable sanitation facilities.
Still, most of its population does not have access to safe and reliable sanitation facilities.
On top of these, the majority of the households do not have sufficient understanding of
hygienic practices regarding food, water, and personal hygiene. As a result, over 75 %
of the health problems in Ethiopia are due to communicable diseases attributed to
unsafe and inadequate water supply, and unhygienic waste management, particularly
human excreta.
The report from (Supply & Programme, 2015),in the world 884 million people use
unimproved drinking water sources in 2010, and in 2015 estimates about 672 million
people will still using unimproved drinking water sources. The (Blumenthal, 2000)
reported that seventy-five percent of all diseases in developing countries arise from
polluted drinking water. The lack of access to water also limits sanitation and hygiene
practices in many households because of the priority given for drinking and cooking
purposes.
Waterborne diseases controlled by different mechanisms. Many studies have clearly
shown that the supply of microbiologically safe water can reduce directly or indirectly,
the morbidity and mortality of diarrhea diseases. Improved sanitation could reduce

. of Gondar Town .
8
diarrheal disease by 32%, whereas hygiene education and promotion of hand washing
were found to reduce by 45 %. Likewise, household water treatments such as
chlorination at point of use can also achieve 35-39% reduction in diarrheal diseases.
Although some naturally occurring microorganisms exist in water, the most important
pollutants of health importance are emanated from domestic and industrial wastes.
These pathogens can cause diseases in humans and animals. They can be bacteria,
viruses, or parasites (Hailu, 2017). Human and animal wastes are primary sources of
bacteria in drinking water. These sources include runoff from feedlots, pastures, and
other land areas where animal wastes are deposited. Additional sources include seepage
or discharge from septic tanks and sewage treatment facilities. Bacteria from these
sources can enter wells that are either open at the land surface or do not have water-
tight casings or caps (Aldener et al., 2006).
Drinking water quality is becoming an issue of global human health concern,
principally due to water contamination with pathogens and potentially toxic chemicals
(WHO, 2005). It has a strong impact on people’s health because water is a means of
transmission for many pathogenic microorganisms that cause diarrhea diseases. In
order to reducedisease outbreaks emanated from polluted water, it is important to
emphasize water quality management (Howard, 2010).
2.2. Performance Evaluation of Drinking Water Treatment Plant
Particulate matter can be removed from raw waters by rapid gravity, horizontal,
pressure or slow sand filters. Slow sand filtration is essentially a biological process,
whereas the others are physical treatment processes. Rapid gravity, horizontal and
pressure filters can be used for filtration of raw water, without pretreatment. Rapid
gravity and pressure filters are commonly used to filter water that has been pretreated
by coagulation and sedimentation. An alternative process is a direct filtration, in which
coagulation is added to the water, which then passes directly onto the filter where the
precipitated floc (with contaminants) is removed; the application of direct filtration is
limited by the available storage within the filter to accommodate solids (WHO 2011).
Turbidity measurements are the most valuable water quality parameters used in
assessing treatment plant performance. A comparison of source water and filtered water

. of Gondar Town .
9
using these procedures has been proposed as a reliable method for determining
treatment plant performance (Bellamy et al., 1993).
The performance of sedimentation and filtration stages in AWTP are evaluated as a
removal efficiency between the turbidity of the raw water and treated water turbidities
in the treatment plant (O'Connor et al,2009).The calculation is a percentage removal as
the following equation
Removal Efficiency (%)
=
Turbidity in raw water − Turbidity in treated water
Turbidity in raw water
x 100% … … … … eq 1
2.3. Factors affecting Water Quality at Distribution Systems
A possible contamination source that carries threats to drinking water quality are open
field defecation, animal wastes, plants, economic activities (agricultural, industrial and
businesses) and even wastes from residential areas as well as flooding situation of the
area. Any water sources, especially older water supply systems, hand dug wells;
pumped or gravity-fed systems (including treatment plants, reservoirs, pressure break
tank, pipe networks, and delivery points) are vulnerable to such contamination.
Particularly systems with casings or caps that are not watertight are most vulnerable.
This is particularly true if the water sources are located close to surface runoff that
might be able to enter the source. An additional way by which pollution reaches and
enters a water supply system is through overflow or infiltration by floodwaters and
inundation of waters commonly contain high levels of contaminants (Haylamicheal &
Moges, 2012).
In water distribution systems, both physicochemical and microbiological indices can
change. Many factors have an effect on secondary contamination of water that can be
supplied to consumers. The type and intensity of processes occurring within water
supply systems decide on the form of contamination (suspended, colloidal or
dissolved). However, the type of concentration of contaminants penetrating into water
depends on the amount and chemical composition of deposits in a water supply system,
the number and kind of microorganisms living in biofilms, microbial metabolic
pathways, biochemical processes and stability of flowing water (Jachimowski, 2017).

. of Gondar Town .
10
2.4. Physicochemical Quality Parameters of Drinking Water
The physiochemical water quality parameters are the ones that are contributed by
climatologically, hydrological and geological factors. They affect the bacteriological,
chemical and physical components of water.
2.4.1. PH
PH usually has no direct impact on consumers; it is one of the most important
operational water quality parameters”. Whenever water treatment or storage is taking
place (arsenic removal, clarification, disinfection, rainwater harvesting), careful
attention to the level of pH is necessary and the optimum pH required is generally
within the range 6.5–8.5 (WHO, 2011) according to the parameter.PH
may be
influenced by various factors and processes, including temperature, discharge of
effluents, acid mine drainage, runoff and decay processes. Low pH levels cause severe
corrosion of metals in the distribution systems while high pH values result in a
progressive decrease in the efficiency of the Chlorine disinfection process.
According to (Zamxaka et al, 2004) pH values ranging from 3 to 10.5 could favor both
indicator and pathogenic micro-organism growth. The overall pH
pattern showed that
the pH values were relatively high in winter compared to summer. Physical parameters,
such as pH, temperature, and turbidity have a major influence on bacterial population
growth
2.4.2. Temperature
Temperature also affects the concentration of dissolved Oxygen and can influence the
activity of bacteria in water bodies. In the analysis of the physiochemical quality of pipe
water samples, temperature considered as a critical parameter affecting many reactions,
including the rate of disinfectant decay and by-product formation. As the water
temperature increases, there is an increase in the disinfectant demand and byproduct
formation, nitrification, and microbial activity. An aesthetic objective is set for the
maximum water temperature to aid in the selection of the best water source or the best
placement for water intake. It is desirable that the temperature of drinking water should
not exceed 15ºC because the palatability of water enhanced by its coolness. Micro-
organisms have been found growing virtually everywhere where there is water,

. of Gondar Town .
11
regardless of its temperature(Zamxaka et al, 2004). Temperatures above 15ºC can speed
up the growth of nuisance organisms such as algae which can intensify taste, odor, and
color problems in drinking water (Hailu, 2017).
2.4.3. Turbidity
Turbidity is a measure of cloudiness of water. It has no health effects. However,
turbidity can interfere with disinfection and provide a medium for microbial growth.
High turbidity may indicate the presence of disease-causing organisms. These
organisms include bacteria, viruses, and parasites that can cause symptoms such as
nausea, cramps, diarrhea, and associated headaches (Mebrahtu et al, 2011).
The turbidity of water is one of the important physical parameters that affect not only
the quality of water but also other chemical and bacteriological parameters and
efficiency of treatment (WHO, 2006). Due to this through process aesthetics,
filterability, and disinfection.
The WHO and EPA (Environment al Protection Authority) guideline value for turbidity
is 5 NTU (Nephelometric Turbidity Unit) and the maximum permissible limit (MPL)
of USA is defined as from 0.1 to 1 NTU on January 23, 2015. As per guidelines for
drinking-water quality by the World Health Organization (WHO), turbidity in water
caused by suspended particles or colloidal matter that obstructs light transmission
through the water. It may be caused by inorganic or organic matter or a combination of
the two. Microorganisms (bacteria, viruses, and protozoa) are typically attached to
particulates, and removal of turbidity by filtration will significantly reduce microbial
contamination in treated water (Hailu, 2017). However, to ensure the effectiveness of
disinfection, turbidity should be no more than one NTU and preferably much lower.
2.4.4. Electrical Conductivity
Electrical conductivity (specific conductance) measures the total concentration,
mobility, valence and the temperature of the solution of ions. It depends on the total
concentration, mobility, valence and the temperature of the solution of ions.
Electrolytes in a solution dissociate into cations and anions and impart conductivity.
Most dissolved inorganic substances are in the ionized form in water and contribute to
conductance. The measurement of the conductance of drinking water samples gives a

. of Gondar Town .
12
rapid and practical estimate of the variation in dissolved mineral content of the water
supply (WHO, 2006). The electrical conductivity of water increases with the
concentration of dissolved solids. Electrical conductivity can be used as a fast method
of indirect measure of TDS, but the factor used to convert EC into TDS will depend on
the type of dissolved solids present in the water (ADWG, 1996).
2.4.5. Total Dissolved Solid
Total solids refer to the presence of materials suspended or dissolved in water and are
related to both electrical conductivity and turbidity (Wright et al., 2010).Total dissolved
solids (TDS) are characterized mainly by major anions and cations such as carbonate,
bicarbonate, sulfate, chloride, Nitrate, sodium, calcium, magnesium, and potassium
(Kucuksezgin, Uluturhan, & Batki, 2008)
Total Solids includes both total suspended solids (TSS), the portion of total solids
retained by a filter, and total dissolved solids (TDS), the portion that passes through a
filter. Concentrations above 500 ppm of TDS may cause adverse taste effects on
drinking water (Nordstrom, Alpers, Ptacek, & Blowes, 2000).
With respect to drinking water quality, water with extremely low TDS concentrations
may be objectionable because of its flat, insipid taste. These may include laxative
effects mainly from sodium, sulfate and magnesium sulfate. The adverse effects of a
high concentration of sodium on certain cardiac patients and kidney function well
documented.
2.4.6. Dissolved Oxygen
Dissolved Oxygen is the amount of Oxygen dissolved in the water and thus available
for aquatic organisms to use. Normal DO levels in freshwater are between 8 and 10
mg/l(APHA, 1992).Oxygen enters the water from the air at the surface of the stream
and enters the water from aquatic plants and algae. It is a by-product of photosynthesis.
The concentration of dissolved Oxygen in a stream is affected by temperature; Oxygen
is more easily dissolved in cold water(Jane Walker, 2006).
Excessive growth of primary producers may lead to a depletion of dissolved Oxygen.
During the day, primary producers provide Oxygen to the water as a by-product of

. of Gondar Town .
13
photosynthesis. At night, however, when photosynthesis ceases but respiration
continues, dissolved Oxygen concentrations decline. Furthermore, as primary
producers die, bacteria that consume Oxygen decompose them, and large populations
of decomposers can consume large amounts of dissolved Oxygen. Many aquatic
insects, fish, and other organisms become stressed and may even die when dissolved
Oxygen levels drop below a particular threshold level (e.g., below 5 mg/l(Wong &
Clark, 1976)
2.4.7. Free Residual Chlorine
Chlorine added to drinking water supplies for the purpose of destroying or deactivating
disease-producing microorganisms. This is termed water disinfection. Chlorine (Cl2)
usually added to water in liquid form or as sodium or calcium hypochlorite chemicals.
Maintaining an adequate level of residual Chlorine is of great importance in terms of
distribution water quality management (Housseini, 2003). The (WHO, 2011), guideline
value for the palatability and health significance of residual Chlorine is 0.5 to 1.5mg/l
in drinking water distribution systems.
The disinfection activity of Chlorine on microorganisms is greatly reduced at high pH,
probably because at an alkaline pH, the predominant species of Chlorine is hypochlorite
ions (WHO, 2011).
Studies have shown that when residual Chlorine levels drop below recommendations,
several water quality problems can occur. With regard to public health, bacteria and
selected viruses called bacteriophage are able to multiply in water that was not properly
disinfected. Moreover, depending on the species, could potentially cause waterborne
diseases. It is important to note that, although chlorination has been the most common
method of disinfection for over many years. While recommendations only state
minimum residual Chlorine levels, it is important that a careful balance maintained in
drinking water. There needs to be enough Chlorine to make sure everything properly
disinfected.
2.4.8. Nitrate and Nitrite
Nitrate is one of the extremely significant disease-causing parameters of drinking water
quality, particularly blue baby syndrome in babies and used as an indicator for the

. of Gondar Town .
14
presence of organics. Nitrates can cause methemoglobinemia at greater than 100 mg/l
where a baby cannot take breaths enough Oxygen (Roberts, 2006) the sources of Nitrate
are nitrogen cycle, industrial waste, nitrogenous fertilizers etc. Nitrate concentrations
above 50mg/l can cause adverse health effects in infants less than three months of age,
and also Nitrate concentrations above 100mg/l can affect pregnant women (Lee,
2012).However, a maximum contaminant level of 50mg/l of Nitrate has been
established for drinking water (Fawell et al., 2006). The WHO guidelines maximum
permissible values of Nitrate in drinking water is 50 mg/l as NO3 for Nitrate and 3mg/l
as NO2 for Nitrite (Alan, 2000).
According to (Reimann et al., 2003)Drinking water samples were collected throughout
the Ethiopian part of the Rift Valley, High NO2 and NO3 concentrations in drinking
waters point often towards contamination. Wells with high NO2 and NO3 values should
be checked for bacterial contamination.
2.4.9. Ammonia
The term Ammonia includes the non-ionized (NH3) and ionized (NH4+) species.
Ammonia in the environment originates from metabolic, agricultural and industrial
processes (WHO, 2003).In nature, Ammonia is formed by the action of bacteria on
proteins and urea. Ammonia makes a powerful cleaning agent when mixed with water.
For this reason, it is one of the most common industrial and household chemical.
Ammonia is rich in nitrogen so it makes an excellent fertilizer. In fact, Ammonium salts
are a major source of nitrogen for fertilizers. Like Nitrates, Ammonia may speed the
process of eutrophication in waterways (Rubio et al, 2007)
In the presence of Ammonia nitrogen ion, free Chlorine reacts in a stepwise manner to
form chloramines, Ammonia concentration was measured at Point of entry, Reservoir
inlets/outlets the end result is important to develop baseline data for prediction of the
onset of nitrification. Degradation of nitrogenous organic matter, industrial and
municipal waste discharges are typical sources of Ammonia.
2.4.10. Phosphate
Phosphorus is a nutrient required by all organisms for the basic processes of life. It is a
natural element found in rocks, soils, and organic material. Its concentration in clean

. of Gondar Town .
15
waters is generally very low (Hashmi, Farooq, & Qaiser, 2009). However, phosphorus
is used extensively in fertilizer and other chemicals, so it can be found in higher
concentrations in areas of human activity. Phosphorus is generally found as Phosphate
(PO4
3-
).
High levels of Phosphate, along with Nitrate, can overstimulate the growth of aquatic
plants and algae, resulting in high dissolved Oxygen consumption. The primary sources
of Phosphates to surface water are detergents, fertilizers, and natural mineral deposits
(Liu, et al , 2008). Inorganic Phosphate is Phosphate that is not associated with organic
material. Types of inorganic Phosphate include ortho Phosphate and poly Phosphates.
2.4.11. Iron
Groundwater usually contains more of Iron minerals than surface water. Iron is irritants
that should be avoided if in excess of 0.3 mg/l. They stain clothing and plumbing
fixtures, and the growth of Iron bacteria causes strainers, screens to clog, and metallic
conduits to rust. The appearance of a reddish brown in a water sample after shaking
indicates, the presence of Iron (Alan, 2000).
2.5. Bacteriological Water Quality Parameters of Drinking Water
The presence of certain microorganisms in water is used as an indicator of possible
contamination and an index of water quality (EPA, 2015). Indicator organisms are
selected to demonstrate the presence of human and animal wastes and hence the
potential presence of pathogens in drinking water. Indicator organisms are usually of
intestinal origin from humans and animals (Savichtcheva and Okabe, 2006).
Therefore, the presence of indicator organisms in water indicates contamination of
water by fecal matter, which could probably contain pathogens such as Salmonella and
Shigella (Chang, 2008).The main groups of bacteria are suggested to serve as indicators
to monitor water quality. These are total coliforms (TC), fecal coliforms (FC)
(Baldursson and Karanis, 2011). The criteria set to identify indicator organisms for
water quality analyses are: the organisms must be exclusive of fecal origin and
consistently present in fresh fecal waste, they must occur in greater numbers than the
associated pathogens, they must be more resistant to environment al stresses and persist

. of Gondar Town .
16
for a greater length of time and they have to be detected on the basis of simple, reliable,
and inexpensive methods (Wingender and Flemming, 2011).
2.5.1. Coliform Bacteria
Total coliforms are the ones that are commonly measured as indicator bacteria for
drinking water quality (Savichtcheva and Okabe, 2006). They are defined as aerobic
and facultative anaerobic non spore-forming bacteria that ferment lactose at 35 to 370C
with the production of acid and gas within 24-48 hours.Coliform bacteria belong to the
family enter bacteria and include Escherichia coli (E.coli) as well as various members
of the general Nitrobacteria, Klebsiella and Citrobacter (Matthiessen and Law, 2002).
These bacteria originate in the intestinal tract of warm-blooded animals and can be
found in their wastes.
They can also be found in soil and on vegetation. Although coliform bacteria are not
pathogens, their presence indicates the possibility of finding pathogens in drinking
water. Consequently, they are used to assess possible fecal contamination or water
pollution from sewage. According to (Savichtcheva and Okabe, 2006),the persistence
of total coliform bacteria in aquatic systems is comparable to that of some of the
waterborne bacterial pathogens. Furthermore, coliform bacteria are relatively simple to
identify and are present in much larger numbers than more dangerous pathogens. For
this reason the degree of fecal pollution and the presumed existence of pathogens can
be estimated by monitoring coliform bacteria (Wheeler et al., 2002).
The total coliform group has been selected as the primary indicator bacteria for the
presence of disease-causing organisms in drinking water. It is a primary indicator of the
suitability of water for consumption. If large numbers of coliforms are found in water,
there is a high probability that other pathogenic bacteria or organisms exist. The WHO
and Ethiopian drinking water guidelines require the absence of total coliform in public
drinking water supplies.
Water is unsafe for human consumption when it contains pathogenic or disease-causing
microorganisms, which are directly transmitted when contaminated fresh water is
consumed. In the study area, the use of water for various purposes (food preparation,
bathing etc.). Without prior treatment was very common. Such practices together with

. of Gondar Town .
17
relative the position of the wells with latrines, a short distance of wells from the latrines
as well as improper protection of the source (wells) were the major identified risk
factors to result in various diseases (including typhoid fever, diarrhea, cholera, and
others) related to consumption of contaminated water.
2.5.2. Fecal Coliforms (Thermo tolerant Bacteria)
Bacteria are found in the subgroup of coliform bacteria that grow at 44°C. Fecal
coliform lives in the intestine of warm-blooded animals. As a result, they show an
excellent positive correlation with fecal contamination of water from warm blooded
animals (Volk and LeChevallier, 2002).
Apart from the fact that the fecal coliform E-coli is considered as one indicator of fecal
contamination of water, some strains such as enter hemorrhagic and intro invasive have
become serious causative agents of emerging waterborne diarrheal disease. The
presence of coliform bacteria in potable water indicates unsuitable sanitation practices.
Such occurrences may be a result of poor water treatment systems, leakages in the
pipelines, and or re-growth in the distribution system (Garcia-Armisen et al., 2006).
The complete coliforms and E-coli microorganisms group could be seat as the primary
indicator bacteria for the presence of disease-causing organisms in drinking water. It is
a primary indicator of suitability of water for consumption. If large numbers of
coliforms could be found in water, there is a high probability that other pathogenic
bacteria or organisms exist. The World Health Organization and Ethiopian drinking
water guidelines require the absence of total coliform and E-coli microorganisms group
in public drinking water supplies. The frequency of testing for public water supplies
depends on the size of the population served. The diseases caused by water-related
microorganisms were divided into four main classes: Waterborne diseases: caused by
water that to be contaminated by human, animal or chemical wastes. Examples include
cholera, typhoid fever, meningitis, dysentery, hepatitis, and diarrhea. A host of
bacterial, viral, causes diarrhea and parasitic organisms most of which can be spread by
contaminated water (WHO, 2006)Poor nutrition resulting from frequent attacks of
diarrhea is the primary cause for little growth for millions of children in the developing
world(Addisie, 2012).

. of Gondar Town .
18
2.6. WHO and Ethiopian Standards of Drinking Water quality
Water is essential to sustain life, and a satisfactory (adequate, safe and accessible)
supply must be available to all. Improving access to safe drinking water can result in
tangible benefits to health. Every effort should be made to achieve drinking water that
is as safe as practicable.
Safe drinking water, as defined by the guidelines, does not represent any significant
risk to health over a lifetime of consumption, including different sensitivities that may
occur between life stages. In the other direction, the nature and form of drinking-water
standards may vary among countries and regions and there is no single approach that is
universally applicable. In the development and implementation of standards, it is
essential to consider the current or planned legislation relating to water, health and local
government and the capacity of regulators in the country. Additionally, approaches that
may work in one country or region will not necessarily transfer to other countries or
regions (WHO, 2011). For this work, WHO and Ethiopian guidelines values for
drinking water are presented in Table 2.1.

. of Gondar Town .
19
Table 2-1: The WHO guideline values of drinking water quality parameters
No Parameter WHO (2011) standard Ethiopian standard
1 PH (ph unit) 6.5-8.5 6.5-8.5
2 Turbidity(NTU) 5 5
3 Free Chlorine residual(mg/l) 0.5-1.5 0.2 - 0.5
4 Fecal coliform(CFU/100ml) 0 0
5 Total coliform (CFU/100ml) 0 0
6 Nitrate (mg/l) 50 50
7 Nitrite(mg/l) 3 3
8 TDS <600 1000
9 Temperature (o
c) <15
10 Iron(mg/l) 0.5 0.3
11 EC(μS/cm) 800 800
12 Dissolved Oxygen(mg/l) 5 5
13 Phosphate(mg/l) 0-4 4
14 Ammonia (mg/l) 0.5 1.5

. of Gondar Town .
20
3. MATERIALS AND METHODS
3.1. Research Design
Experimental study and a cross-sectional study design semi-structured questionnaire
through an interview to collect data regarding water-borne diseases would be applied
for the completion of this study. This experimental study design was used for assessing
the physiochemical and bacteriological quality of potable water at sources of treated
Angereb water, Kolladeba and springs, and consumers tap users with different pressure
zones. The study was conducted from the first week of every month from April 2017
to March 2018. From raw water to potable Recorded data was used Performance
evaluation of treatment plant used for a period of 2012 up to 2016. All water samples
from their source were collected using polyethylene sampling bottles were washed
toughly with distilled water to avoid contamination and leveled it to understand where
is the sites of samples were collected. Water samples after collected have been
transported to the laboratory of Angereb water treatment plant using icebox for the
analysis. At the time of samples collecting, pH, turbidity, electric conductivity, total
dissolved solids, dissolved Oxygen were measured in the situ by using models of the
WP 600 Series meter (multi-Parameter). Ammonia, Nitrate, Nitrite, Phosphate, heavy
metals (Fe), have been recorded their values by using UV- 7100 Photometer with their
reagents. The bacteriological analysis of the sample has been analyzed using all
bacteriological materials water sucker kit, filter paper, Petridis, absorbents pad, the
culture media which is source of food for bacteria and the incubator to incubated
bacteria based on coliform type and at its temperature (370
c) for total coliform and 440
c
for fecal coliform/ 100 ml water). There are two distinct seasons; wet season between
June and September and the dry season starts from October to April. The study was
conducted by field observation (observing the source, treatment and distribution
systems on the field to estimate the status), and laboratory analysis (experimental).
3.2. Description of the Study Area
Gondar Town, former capital of North-Western Ethiopia during the reign of Emperor
Fasilidas (1632-1667), is located in the northwestern part of Ethiopia at a distance of
737 km from Addis Ababa, the national capital, 180 km north of Bahir Dar, the regional
capital, and 250 km from Gedarif, the Sudanese border town. The city has a latitude

. of Gondar Town .
21
and longitude of 12°35’ N and 37°27′E respectively. The town is linked to a
neighboring country Sudan via Metema and as a result, expected as a promising center
for the transit of goods and services with Sudan. The total coverage area of the town is
approximately 51.27 square kilometers. The town is endowed with many historical sites
registered by UNESCO at the international level and it provides good stimulus to the
economy by attracting tourists to the area.
Population Characteristics of Gondar town according to the 2007 National Census
Report, which was compiled in the year 2008 the total population of the Town is
206,987 (CSA, 2008) and the average annual growth rate is 4.69%. The total population
of the town in 2018 is estimated to be 342,690; the 2007 CSA report has been taken as
baseline for this projection
Rainfall of Gondar is characterized as mono-modal type. The annual rainfall varies
from 711.8 to 1822.42 mm with a mean annual value of 1200mm. Long-term
distribution of rainfall data indicates that most of the rain occurs in July followed by
August. The rainfall in May and June is also quite significant. The mean annual
temperature in Gondar Town varies between 16˚C and 20˚C, which makes it in Weina
Dega zone. Maximum temperature occurs in March and April and minimum
temperatures are at their lowest in November to February (GTWSSS, 2017).

. of Gondar Town .
22
Figure 3-1: Location map of Gondar town.
3.3. Water Supply and Sanitation
At present, the city of Gondar is mainly supplied by surface water (Angereb) reservoir,
Kolladeba boreholes, and groundwater (boreholes located in Angereb Valley) wells and
springs.

. of Gondar Town .
23
The current water distribution system of Gondar Town consists of the two main
components. In the system, water is distributed to consumers in the following ways:
 Gravity distribution system
 Distribution by means of pumps with storage (pumping + gravity)
Consumption data of each customer were collected from the computerized bill
information report 2017. There are 29,300 active customers within the entire town in
the year 2017 GC.
Table 3-1: Existing Water Supply Sources
No
Water supply
Components
Discharge
(l/s)
Geographical Location Status
Easting Northing Elevation
1 AWTP 90 335238 1394194 2118
2 NW-1 5.2 335282 1394148 2133
3 NW-2 2.56 333561 1391522 2034
4 NW-3 7 333854 1391779 2043
5 NW-4 4.5 334005 1392232 2048
6 TW-5 3 334203 1392539 2060
7 NW-5 18 334485 1392662 2064
8 GTW-7 20 334540 1392928 2067
9 TW-6 4 335364 1393699 2088
10 TPW-4 20 318820 1371187 1805
11 TPW-5 32 318110 1371658 1811
12 TPW-7 28 319362 1370949 1803
13 TPW-8 30 318949 1370592 1802
14 TPW-9 38 319551 1370466 1802
15 TPW-10 30 319363 1369913 1802
16 TPW-11 40 319712 1369616 1800
17 Azezogomengie 0.98 330595 1395732 2328
18 Sanita 0.74 033075 139489 2282
19 Eudmit 0.45 330505 1395766 2339
20 Gondarochgiworgies 0.87 322489 1397314 2303
Source: Gondar Town Water Supply Service Office (GTWSSO), 2017.

. of Gondar Town .
24
Raw water from Angereb dam is lifted to the rapid sand filtration treatment plant by the
raw water pumps installed in the intake tower. After the water is chlorinated, the clear
water will transfer to the clear water tank through gravity. Water from boreholes in
Angereb Valley is also pumped into this clear water tank. The water is then lifted to
Debre Birhan Sillasie Reservoir by four duty and two standby centrifugal surface
pumps. The water distribution system of the Town contains service reservoirs,
distribution pipes, and pressure break tanks at different locations. There are two
transmission mains conveying water from point of production to reservoirs. The first
main is running from boreholes situated in the Angereb field to the Clearwater tank in
the compound of the treatment plant and the second main is the one conveying water
from the clear water tank to Debre BirhanSillasie Reservoir.
3.4. Pressure Zones in Distribution Systems
The distribution system of the Town is subdivided into nine zones were established by
combining sub-city boundaries and pipelines. Through each pressure zone is supposed
to have its own dedicated reservoir and distribution pipes, some of the distribution pipes
of different zones are interlinked making the system inefficient. Besides, there is no
well-documented map showing the extent of each distribution line and the service
boundary of the reservoirs. According to an inventory report of the GTWSS office, the
total estimated length of distribution pipes in the Town is greater than 120km with
varying pipe size.
AutoCAD and ArcGIS software packages were used to overlap the distribution system
with the appropriate location of pressure zones. System maps are drawn as a
combination of various system components enclosed in the distribution system. Figure
3-2 below illustrates layout of Gondar distribution pressure zones and reservoir cover
areas.

. of Gondar Town .
25
Figure 3-2: Map showing pressure zones and reservoir cover areas
Through each pressure zone is supposed to have its own dedicated reservoir and
distribution pipes, some of the distribution pipes of different zones are interlinked
making the system inefficient. Obviously, the importance of reservoir as part of the
distribution system is to guarantee a continuous supply of water at the time of
interruptions in the process of production. This indeed, depends on the number and
capacity of reservoirs and on the relative ground elevation where they are situated, if
water is to be distributed by gravity.

. of Gondar Town .
26
Table 3-2: Water reservoirs (GTWSSO, 2017)
No
Name of
Reservoir
Capacity
(m3
)
Pressure
zones
Kebele Geographical Location
1 Debre
BirhanSillasie
2,000 2 01 334830 1394475 2265
2 Karanio 300 5 02 333841 1395079 2248
3 Gebriel
(WenfitTerara)
1,000 3 14 332978 1395103 2208
4 Stadium 500 6 15 332994 1395367 2155
5 Azezo 1,000 5 19 329076 1388549 2105
6 SamunaBer 500 7 18 330776 1392383 2187
7 Goha 300 1 01 333695 1395503 2276
8 Lozamareyam 2000 8 20 327584 1388770 2180
9 Teklehayemanot 500 9 20 330412 1386820 2110
3.5. Existing Angereb Water Treatment Plant
There are six chemical preparation tanks; out of which four of them are made of HDPE
for alum and sodium carbonate and the other two are made of PVC reinforced with
glass fiber for calcium hypochlorite. All preparation tanks have equal size of 1.4 meters
in diameter and 1.9 meters high with a capacity of 2,800 liters. The solid chemical is
dropped (on the PVC screen tray fixed for alum only) in the tank so that water percolates
through to dissolve them. Each tank has an electrically driven stirrer and a lid is
provided, which is opened when putting chemicals into the tank.
Figure 3-3: Chemical preparation tanks and control panel in the chemical building

. of Gondar Town .
27
Alum, calcium hypochlorite and soda ash solutions are designed to be prepared in daily
tanks (the others are as standby) in the chemical building, each one fitted with levels
witch. Each stirrer is controlled by on/off button box near the tank and the switch panel
placed in the chemical building will enable to select the tank that is on duty. The low
levels, which activates a signal, light on the control panel of the chemical building, to
indicate that the tank is empty. The low-level switch stops the mixer on duty for
protection.
The chemical solution feeding system installed designed to deliver the solution to the
application point by gravity with the help of constant head gravity type chemical doses.
Figure 3-4: Rapid mixing chamber and chemical dosing arrangement
The rapid mixing chamber is made of concrete, has a volume of about eight m3. The
treatment plant has an open channel hydraulic rapid mixer type. This rectangular weir
within the chamber is designed to be used as a flow-measuring device as well as to
create a sudden drop in the hydraulic level to induce turbulence in the water for rapid
mixing too. The original design and installation were supposed to apply chemical
solutions at this plunge point with the help of gravity dosage regulator. Water from the
hydraulic mixing chamber flow into the coagulation and flocculation Chambers by
gravity

. of Gondar Town .
28
Figure 3-5: Picture of baffled flocculation tanks
Figure 3-6: Rapid Sand clarifiers
The disinfection takes place after the treated surface water is entering the post-
chlorination chamber. The calcium hypochlorite solution, prepared in the chemical
building, flows by gravity through the pipe hose similar to the alum and pre chlorination
feeding system. The untreated groundwater coming from the Angereb valley boreholes
and the remaining disinfection process for the filtered water is carried out in this
chamber.

. of Gondar Town .
29
Similar type constant head gravity dosage regulator (flow adjustable between 10-140
l/h) was designed and installed to feed solution at the dosing point, even though they
are currently out of order. According to the observation done on the treatment plant and
recorded data, the main disinfection have been done at pre chlorination point.
Gondar Water Treatment Plant is a conventional treatment plant treating both surface
water and groundwater. Groundwater from the wells joined the treated surface water in
the clear water reservoir and disinfection in the reservoir.
Figure 3-7: Angereb Water Treatment Plant layout and scheme
Figure 3-8 below shows the main components of the treatment plant
Figure 3-8: Components of Angereb Water Treatment Plant

. of Gondar Town .
30
3.6. Materials
3.6.1. Source of Data
The primary data was collected samples grabbed at different locations that were
randomly selected sampling sites from the source water at Treated Angereb reservoir,
Kolladeba reservoir, and springs and selected household taps. There are two distinct
seasons; wet season between June to September and the dry season starts from October
to May. In dry season and wet season at 35 randomly selected sites, sampled water was
taken and laboratory analysis was conducted on physiochemical and microbiological
water quality parameters.
Water sample that collected was analyzed for different parameters at Gondar Town
Water Supply and Sewerage office laboratory. Secondary data were collected from
published and unpublished literatures and from office reports.
3.6.2. Sample Size and Sampling Points
Samples were taken from locations that are representative of the different treated water
source, distribution network, points at which water is delivered to the consumer, and
points of use. In selecting sampling points, each locality was considered individually;
however, the following general criteria are usually applicable:
Sampling points should be selected in such a way that the samples taken are
representative of the different sources and points of distributions. These points should
include the samples representative of the conditions at the most unfavorable sources or
places in the supply system, particularly points of possible contamination such as
rawand treated water sources, reservoirs, and low-pressure zones end. The location of
sample points selected in this study are shown in figure as depicted below the sampling
points are located enclosed delineated map of the study area as shown in figure 3-9.
A Geographical positioning system (GPS) was used to collect the spatial data and
ArcGIS 10.1 software was used to locate the geographical location of sampling points
in the study area.
Gondar town with a population of 342,690. GTWSSO registered 29,300 housing units
having a customer of drinking water distributed to town. From total customers, 32

. of Gondar Town .
31
household containers water analyses were selected randomly from customer bill
numbers. The sampling distribution, dependence on their weight proportion of bill
numbers in each Keble customers’ of GTWSSO (Table 3.3).
A total of 490 water samples were collected with replication from the study area. The
Samples were taken from locations that were representative of the water sources of
Kolladeba reservoir, Angereb treated reservoir, springs and household taps. Water
samples from 3 water sources and 32 private taps within nine different pressure zones,
the samples were collected for a period of one year in the first week of every month.
The simple random sampling method was used to determine representative sampling
points. The 32 private taps were randomly selected from all the nine-pressure zone of
the town.

. of Gondar Town .
32
Table 3-3: Number of sampling site with its pressure zone location.
Pressure
zone
reservoir No of
customers
Sampling
number
Sampling location
1 Goha 2715 3 334108 1395747 2254
334204 1394893 2244
333348 1395111 2204
2 Debre
Birhan
Sillasie
4253 5 335272 1394165 2132
334864 1394481 2212
335522 1392861 2182
333141 1392420 2090
333219 1393600 2204
3 Gebreal 3725 4 332967 1393946 2172
333743 1394716 2202
333472 1394851 2180
332617 1395579 2166
332568 1394415 2122
4 Stadium 2853 3 331415 1393951 2148
332438 1391828 2060
330773 1392383 2124
5 Karaniu 2978 3 330559 1392410 2190
330442 1392944 2270
330631 1391462 2106
6 Samunaber 2918 3 330178 1392486 2148
330107 1391982 2136
330385 1390728 2102
7 Loza
Maaryam
2215 2 327880 1386279 2114
327507 1387794 2154
8 Azezo 4845 5 329064 1388518 2084
329268 1389101 2078
327536 1388768 2102
330675 1387666 2010
329166 1387323 2032
9 Teklehayem
anot
2898 3 330005 1386810 2046
330307 1385571 1970
330267 1384468 1936
The samples were collected in dry season and wet season. Samples were taken from
locations that were representative of the Kolladeba reservoir, Angereb treatment
reservoir, springs and for distribution system at household taps with different pressure
zones connections. Purposively sampling method was used to determine representative
sampling points (Daniel, 1995). The private taps were systematically selected from
selected pressure zones.

. of Gondar Town .
33
Figure 3-9: Location of sampling sites in Gondar town
3.6.3. Equipment and Reagents
Gondar Town Water Supply and Sewerage Service laboratory materials/Equipment
was used for water quality analysis. To measure accurately the physical, chemical and
biological characteristics of water are stated as follows;Refrigerator, wash bottles,
graduated measuring cylinders, Erlenmeyer flasks, beakers, Pipette, funnel,
polyethylene bottles, distiller, Petridis, Absorbent pad, membrane filter paper, water

. of Gondar Town .
34
sucking, tong, gloves, 10 ml glass (WE 10755), 100 ml test tube, auto cleave, bacteria
incubator, WP B600 series were used for test Electrical Conductivity (EC), PH
,
Turbidity, Total Dissolved Solids (TDS) and Temperature andUV-7100 Photometer
were used for test the rest selected physiochemical parameters.
Reagents that are required in the laboratory to assess the quality of water including
Nitric acid, the reagents; Nitrates powder, Nitricol, Hardcol,Coppercol, Manganese
tablet ,Magnicol , Calcicol, Iron HR, Chloridol, Fluoride tablet, Sulphate tablet,
Phosphate HR, Ammonia,Alkaphote,and distilled water.
The physiochemical analysis was important to follow the instructions on storage and
protection in the manual. Microbiological analysis was also undertaken in the same
laboratory, using validated membrane filtration techniques. The main procedure was
incubating the sample water in a media, which selectively promotes the growth of total
coliform bacteria and fecal coliform.
UV- 7100 Photometer WP 600 Series meter
Figure 3-10: Some equipment used in the field and laboratory Study

. of Gondar Town .
35
3.7. Methods
The thesis structure has the following conceptual settings to achieve the predefined
goals in the study.
Figure 3-11: Research methodology process diagram
3.7.1. Data Collection
The method of sample collection was according to WHO drinking water guideline
(WHO, 2006). Water samples were collected starting from April 2017 to March 2018
in the first week of every month. All water samples from their source were collected
using polyethylene sampling bottles were washed toughly with distilled water to avoid
contamination and leveled it to understand where is the sites of samples were collected.
Data collection methods Discussion with town utility and
organizations
Field observations Field Data
Collection
Gathering information primary
and secondary data
Research methodology
Data analysis using Microsoft Excel
Evaluate the Performance of treatment plant
Result and
discussion
Conclusion and
recommendation

. of Gondar Town .
36
Water samples after collected have been transported to the laboratory of Angereb water
treatment plant using icebox for the analysis. At the time of samples collecting, pH,
turbidity, electric conductivity, total dissolved solids, dissolved Oxygen were measured
in situ by using models of the WP 600 Series meter (multi-Parameter). Total hardness
(ion of calcium and magnesium), Ammonia, Nitrate, Nitrite, Phosphate, Iron, have been
recorded their values by using UV- 7100 Photometer with their reagents. The
bacteriological analysis of the sample has been analyzed using all bacteriological
materials (water sucker kit, filter paper, Petridis, absorbent pad, the culture media which
is source of food for bacteria and the incubator to incubated bacteria based on coliform
type and at its temperature (370
c for total coliform and 440
c for fecal coliform/ 100 ml
water).
3.7.2. Data Analyses
Water quality analyses of different water quality parameters were done by evaluating
the test value with respect to drinking water guideline value (National and
International). Water samples were taken from at the treated Source and Reservoir and
Distribution System Within nine different pressure zones. Essential physical, chemical
and biological water quality parameters (temperature, Turbidity, PH, EC, DO, TDS,
free Residual Chlorine, Nitrate, Nitrite, Phosphate, Iron, Ammonia, FC and TC were
conducted a test at Gondar water treatment laboratory.
3.7.2.1.Physiochemical Analyses
Temperature, pH, turbidity, electric conductivity, total dissolved solids, dissolved
Oxygen were measured in the situ by using models of the WP 600 Series meter (multi-
Parameter).
For Iron measurement: filled the test tube with a sample to the 10 ml marked. Added
on Iron MR no.1 tablet crushed and mixed well. Added one Iron MR no.2 tablet crushed
mixed well to dissolved Stand for 10 minutes to allow full color developed. By selected
wavelength 520 on photometer and taken the reading on photometer.
For total hardness measurement: filled the test tube with a sample to the 10 ml marked
and then added one Hardicol no. 1 tablet crushed and mixed well and added one
Hardicol no. 2 tablet crushed and mixed it and then stand for 2 minutes to allow full

. of Gondar Town .
37
color development. Select photo number 15, insert the test tube on it, and recorded the
reading value.
For Phosphate measurement: filled the test tube with a sample to the 10 ml marked and
added one Phosphate SR tablet, crushed and mixed and then added one Phosphate HR
tablet, crushed and well mixed. Stand for 10 minutes to full color developed, Select
photo 29 on photometer, and recorded the reading value on it.
For Nitrate measurement: filled the test tube with a sample to the 20 ml marked and
then added one spoonful of Nitrate test powder and one Nitrate test tablet. Was not
crushed the tablet here but only screw cap, shake the tube well for exactly 1 minute and
was allowed contents to settle then invert tube gently 3 times and then allowed stand
for 2 minutes to ensure completely settlement. Removed screw cap, wiped round top
with a clear tissue, and then decanted clear solution in to the 10 ml test tube marked.
Added one nitricol tablet crushed, well mixed, and stands for 10 minutes. Select
wavelength 520 nm on the photometer, insert the test tube on it, and recorded the
reading value.
For Nitrite measurement: Filled the test tube with sample to the 10 ml marked. Added
one nitricol tablet crushed, well mixed, and stands for 10 minutes. Select wavelength
520 `nm on the photometer and insert the test tube on it and recorded the reading value.
For Ammonia measurement: Filled the test tube with sample 10 ml marked, then added
one Ammonia no.1 tablet and one Ammonia no. 2 tablet, crushed and mixed to dissolve
and then stand for 10 minutes Select wavelength 640 nm on the photometer and insert
the test tube on it and recorded the reading value.
3.7.2.2.Bacteriological Analyses
For bacteriological parameters, water samples were analyzed using a membrane
filtration (MF) method to determine the degree of contamination. All water samples
were analyzed to know indicators of total coliforms (TC) and fecal coliforms (FC). One
hundred milliliters of a water sample for each test was filtered through a sterile cellulose
membrane filter with a pore size of 0.45μm to retain the indicator bacteria.

. of Gondar Town .
38
For total and fecal coliform measurement: total and fecal coliforms were determined by
taken sterilized water sucker with all its accessory that include tong and added
membrane filter paper on it by the help of tong and loaded its accessory part on it which
has volume level mark. Filled it with the sample to 100 ml marked and allowed to pass
the sample through it. The filter paper that contains some reaming part on it was taken
and put at sterilized Petri-dish that contains culture media with absorbent pad. The
closed Petridis was taken into bacteria incubator by adjusted them incubate temperature
at which 37ºC for 18-24 hours for total coliforms and 44ºC for 18-24 hours for fecal
coliforms.
3.8. Statistical Application
A computer program was used to analyze tabulated data using Microsoft Excel and
SPSS version 21. Descriptive statistics like percentage, mean, standard deviation and
range were used to describe the findings. ANOVA for dependent variables at P≤0.05
significance level was also used to indicate the significant difference between
parameters.

. of Gondar Town .
39
4. RESULTS AND DISCUSION
4.1. Temporal Variation of Water Quality Parameters at Different
Sampling Sites
The water quality status of GTWSS were presented in table 4-1 below. As the result
indicated, in all sampling site parameter like PH, Turbidity, EC, TDS ,Fe, NO3
-
,NH3
and NO2–were within the WHO standard limit whereas, the other parameters were
above the permissible limit. Parameters like TDS, EC, TC and FC concentration
showed increment from Kolladeba to treated Angereb reservoir and springs. This could
be a good indicator of possible source of water contamination at sampling site.
Treated Angereb reservoir, Kolladeba reservoir, springs and tap users PH value for dry
season are7.70, 7.86, 7.57and 7.65 and wet season are 7.56, 7.88, 7.28 and7.25
respectively.Treated Angereb reservoir, Kolladeba reservoir, springs and tap users
Turbidity value for dry season are 0.15, 0.45, 0.58 and 0.28 and wet season
are0.90,1.81,1.92 and1.74 respectively.Treated Angereb reservoir, Kolladeba
reservoir, springs and tap users EC value for dry season is 441.94, 483.237, 487.18and
490.5 and wet season is 406.9, 430.33, 443.95and 421 respectively.Treated Angereb
reservoir, Kolladeba reservoir, springs and tap users TDS value for dry season are
220.97, 188.88, 211.68 and 240.41 andwet season are203.45, 188.19, 223.78 and
231.91respectively.Treated Angereb reservoir, Kolladeba reservoir, springs and tap
users DO value for dry season are6.06, 3.08, 3.41and 5.06 and wet season are5.93,
2.72, 3.27 and4.01 respectively.Treated Angereb reservoir, Kolladeba reservoir,
springs and tap users TC value for dry season are0.00, 0.63, 0.00 and 0.88 and wet
season are0.00, 2.83, 0.83 and2.24 respectively. Treated Angereb reservoir, Kolladeba
reservoir, springs and tap users FC value for dry season are0.00, 0.00, 0.00 and0.34 and
wet season are0.00,0.01, 0.00 and 0.75 respectively. Treated Angereb reservoir,
Kolladeba reservoir, springs and tap users Iron value for dry season are0.02, 0.03,
0.11and 0.06 and wet season is 0.04,0.07,0.13 and0.23 respectively.Treated Angereb
reservoir, Kolladeba reservoir, springs and tap users FRC value for dry season are0.94,
0.86, 0.00 and0.22 and wet season are0.96,0.90,0.00 and0.22respectively. Treated
Angereb reservoir, Kolladeba reservoir, springs and tap users Phosphate value for dry
season are4.89, 7.31, 16.01and 6.96 and wet season are 8.98, 8.11,16.08 and8.74
respectively. Treated Angereb reservoir, Kolladeba reservoir, springs and tap users

. of Gondar Town .
40
Nitrate value for dry season is 13.20, 14.69, 13.69 and14.31 and wet season is
22.37,23.18, 22.60 and23.47 respectively. Treated Angereb reservoir, Kolladeba
reservoir, springs and tap users Nitrite value for dry season are0.01, 0.08, 0.24 and0.03
and wet season are0.01,0.05, 0.25 and0.03 respectively.Treated Angereb reservoir,
Kolladeba reservoir, springs and tap users Ammonia value for dry season are0.01, 0.04,
0.26 and0.08 and wet season are0.04,0.04, 0.25 and0.16 respectively.
Table 4-1: Drinking water quality compliance with the WHO permissible limits in the dryseasons
(Oct-May) and wet seasons (Jun-Sep) in Treated Angereb reservoir, Kolladeba Reservoir, spring
and Tap users Average pressure zones.
No Parameters Gondar potable water sources
Tap users
WH
O
Treated Angereb
reservoir
Kolladiba
Reservoir
Springs
Dry Wet Dry Wet Dry Wet Dry Wet
1 pH ( Ph unit) 7.70
±0.21
7.56
± 0.37
7.86
±0.16
7.88
±0.28
7.57
±0.09
7.28
±0.05
7.65
±0.11
7.25
±0.22
6.5-
8.5
2 T (C°) 23.56
±1.08
23.17
±0.41
25.80
±0.87
25.81
±0.55
23.11
±0.96
22.61
±0.69
20.97
±0.47
20.15
±0.71
<15
3 Tur (NTU) 0.15
±0.01
0.90
±0.26
0.45
±0.32
1.81
±0.18
0.58
±0.14
1.92
±0.46
0.28
±0.06
1.74
± 0.07
1.5
4 EC (μS/cm) 441.94
±32.06
406.9
±18.37
483.23
±16.28
430.33
±1.13
487.18
±14.09
443.95
±5.07
490.5
± 4.00
421
±15.44
400-
1200
5 TDS (mg/l) 220.97
±16.03
203.45
±9.19
188.88
±14.63
188.19
±7.01
211.68
±3.5
223.78
±30.34
240.41
±20.15
231.91
±9.60
<600
6 DO (mg/l) 6.06
±0.11
5.93
±0.16
3.08
± 0.14
2.72
± 0.11
3.41
±0.22
3.27
±0.22
5.06
±0.17
4.01
±0.04
5
7 TC(cfu/100m
l)
0.00
±0.00
0.00
±0.00
0.63
± 0.41
2.83
±1.26
0.00
±0.00
0.83
±0.50
0.88
±0.13
2.24
±0.24
0
8 FC
(cfu/100ml)
0.00
±0.00
0.00
±0.00
0.00
± 0.00
0.01
± 0.02
0.00
±0.00
0.00
±0.00
0.34
±0.10
0.75
±0.03
0
9 Fe (mg/l) 0.02
±0.00
0.04
±0.01
0.03
±0.01
0.07
±0.01
0.11
±0.05
0.13
±0.06
0.06
±0.03
0.23
±0.05
0.3
10 FRC (mg/l) 0.94
±0.02
0.96
±0.15
0.86
±0.06
0.90
±0.12
0.00
±0.00
0.00
±0.00
0.22
±0.10
0.22
±0.02
0.5-
1.5
11 PO4 (mg/l) 4.89
±1.64
8.98
±0.56
7.31
±0.83
8.11
±0.22
16.01
±0.94
16.08
±2.90
6.96
±0.22
8.74
±0.91
0-4
12 NO3(mg/l) 13.20
±0.81
22.37
±2.30
14.69
±4.01
23.18
±0.71
13.69
±1.53
22.60
±1.40
14.31
±1.15
23.47
±2.56
50
13 NO2
–
(mg/l) 0.01
±0.01
0.01
±0.01
0.08
±0.03
0.05
±0.00
0.24
±0.01
0.25
±0.00
0.03
±0.00
0.03
±0.01
0.5
14 NH3(mg/l) 0.01
±0.00
0.04
±0.05
0.04
±0.03
0.04
±0.00
0.26
±0.09
0.25
±0.10
0.08
±0.02
0.16
±0.03
0.5

Seid_Sitotaw_March_2019_Final_Thesis.pdf

Seid_Sitotaw_March_2019_Final_Thesis.pdf

Recommandé

Recommandé

Contenu connexe

Similaire à Seid_Sitotaw_March_2019_Final_Thesis.pdf

Similaire à Seid_Sitotaw_March_2019_Final_Thesis.pdf (20)

Dernier

Dernier (20)

Seid_Sitotaw_March_2019_Final_Thesis.pdf