This document provides information on collecting, storing, and treating rainwater. It discusses the benefits of rainwater harvesting such as being a primary water source, recharging aquifers, and providing water security. Various components of a rainwater harvesting system are described, including collection surfaces, conveyance methods, first flush diverters, storage containers, and pumping systems. Methods for calculating rainfall catchment and storage sizes are presented. Basic maintenance and treatment options like chlorination and filtration are also covered. The overall document serves as a guide for setting up a rainwater harvesting system.

1. Catch the Rain
with Jeremiah Kidd
San Isidro Permaculture
In an animal or plant, 99 molecules in 100 are water…An
organism is a pool in a stream of water along which
metabolites and energy moves through ecosystems.
W.V. Macfarlane

2. Why catch rainwater?
 Primary Source
 Naturally distilled
 Saves energy and
chemicals
 Recharge aquifer
 Reduce erosion and runoff
 Water security
Human Impacts Institute.
2012

3. Why catch rainwater
 Store for dry season
 Multiple Uses
 Self Reliance
 Plants benefit
 Contains N and P
 Remote areas
 Free
 Conserves aquifers

4. Benefits to the Environment
 EPA ranks urban runoff and storm sewer discharge as
second main source of water quality impairment in
estuaries and fourth in our lakes
 James, William “Green roads: Research into Permeable Pavers”
2002
 “…have shown that up to 70% of the pollution in our
streams, rivers, and lakes is carried there by stormwater,”
 (Raingardens.org)

5. Benefits to the Environment
 “contributes to a yearly loss of rainwater infiltration
ranging from 57 to 133 billion gallons. If managed on site,
this rainwater—which could support annual household
needs of 1.5 to 3.6 million people—would filter through the
soil to recharge aquifers and increase underground flows
to replenish rivers, streams, and lakes,”
 Paving our Way to Water Shortages (American Rivers, Natural
Resources Defense Council 2002.

6. Misconceptions
 No recharge
 Too little
 Mosquitoes
 Deprives lakes
 Eyesore
 Too complicated/ expensive
 Must use tanks
Bill Abell 2009

7. Physical Properties of Rain Water
 Water seeks the lowest point and path of least resistance
 Conserve energy by storing at highest point possible for
pressure, .43 psi per 1’ elevation,
1 psi=2.31 feet of elevation
 One gallon of water weighs 8.3 lbs, 3.8 kg
 One liter of water weighs 2.2 lbs, 1 kg
 There is 7.48 gallons per cubic foot of water
 There is 1,000 liters per cubic meter of water
 Lower pH than groundwater in the arid areas

8. Qualities of Rain Water
 Precipitation is the primary source of fresh water within our
planet’s hydrological cycle.
 Precipitation is naturally distilled through evaporation prior to
cloud formation, and thus is one of our purest sources of water.
 Rain is considered soft due to the lack for calcium carbonate or
magnesium in solution and is excellent for cooking, washing
and saving energy.
 Rainwater is a natural fertilizer – picks up N & P
 Rainwater has the lowest salt content of natural fresh water
sources so it is a superior water source for plants.

9. Water Harvesting Principals
 Begin with long and thoughtful observations.
 Start at the top (highpoint) of your watershed and work
your way down.
 Start small and simple.
 Slow, spread, and infiltrate the flow of water.
Brad Lancaster:
www.harvestingrainwater.com

10. Water Harvesting Principals
 Always plan an overflow route, and manage that overflow
as a resource.
 Maximize living and organic groundcover.
 Maximize beneficial relationships and efficiency by
“stacking functions”.
 Continually reassess your system: the feedback loop.
Brad Lancaster:
www.harvestingrainwater.com

11. Design starts with observation
 What is the rainfall patterns: wet, dry





seasons
How much average rainfall in your area?
Where are there catchment surfaces?
What is the elevations of the catchment
surfaces in relation to point of use?
What is the vegetation growing above and
below catchment surfaces?
Taste and smell experience difference from
city or well supply

12. Planning a water harvesting
system
1.
What will the water be used for?
2.
How much rain falls in a year?
3.
How much water is consumed?
4.
The area of roof or other catchment available?
5.
What size storage can be built?
6.
Where to place the storage relative to the catchment and
point of use.
7.
Budget/resources available

14. Parts of a system
 Collection Surface – Roofs, Patios, etc
 Conveyance – Gutters, Downspouts, Piping
 Filtration – Screens, First Flush
 Storage Containers – Tanks, Ponds, Soil
 Other Parts – Pumps, Pressure Tanks
 Overflow – Rain Garden, Swales, Pond
 Water Usage – Domestic, Toilet, Irrigation

16. Collection surfaces

17. Preferable Surfaces
 Acceptable roofing materials are slate, terra-cotta tile,
copper, untreated wood shingles, concrete, and metal
painted with an epoxy paint.
 Unacceptable materials are asphalt shingles, older
concrete tiles (which can contain asbestos), tar, or treated
wood shingles.
 Asphalt shingles are by far the most common roofing
material. Unfortunately, they leach toxins into the water
that runs off them.
 If you have asphalt shingles, think of other options or
apply acceptable surfaces on some or your home.

18. Roof Catchment

20. Shingle Conversion

21. Conveyance
 Gutters, Downspouts, Piping

22. Roof to Tank

23. Catch Boxes

24. First Flush Examples
Courtesy of HarvestH2O.com

25. First Flush Sizing
 1-2 gallons per 100 sq.
ft. of roof area.
 5-10 gal per 1000 sq. ft.
 A 1’ length of 3 inch pipe
holds approximately
0.74 gallons
 A 1’ length of 4 inch pipe
holds approximately
1.30 gallons

26. Pre Tank Filtering

27. Storage Containers – Tanks

28. Water Wall Tank

29. Above Ground Tank

30. Partially Buried Poly Tank
SIP 2011

31. Buried PE Tank
SIP 2011

32. Linking Cisterns in Parallel

33. PE Tank in Parallel
SIP 2011

34. Access Risers & Venting

35. Ferro-Cement Tanks

36. Ferro-Cement Tank Uganda

37. Finished 79,800 liter Tank!

38. Post Installation Inspection

39. Tank Parts

40. Monthly Precipitation
Charleston, West Virginia
 Jan
 Feb
 Mar
 Apr
 May
 Jun
 Jul
 Aug
 Sept
 Oct
 Nov
 Dec
 Total:
3.00”
3.31”
3.91”
3.24”
4.80”
4.29”
4.94”
3.74”
3.25”
2.67”
3.73”
3.27”
44.15”
The driest month is October with
2.67” of precipitation, and with
4.94” July is the wettest month.

41. Calculating Catchment
Charleston, West Virginia
Average Annual Rainfall ~ 44.15”
Method 1:
1000 sq. foot house X
44.15” rainfall (average annual rainfall) /
12 (12 inches per cubic foot) =
3,679 cubic feet of water
3,679 (cubic feet) X
7.48 (7.48 gallons per cubic foot of water) =
27,519 gallons per year

42. Calculating Catchment
Charleston, West Virginia
Total Annual Rainfall ~ 44.15”
Method 2:
Catchment Area (square feet) X
Average Rainfall (ft) X
7.48 (gallons per cubic foot) =
Total Rainwater (gallons)
1,000 square feet X
3.679’ (44.15” / 12) X
7.48 (gallons per cubic foot) =
27,518.92 gallons per year

43. CATCHMENT AREA
in squarefeet
28’x33’=924 f2
X
RAINFALL
44.15” /
feet = 3.8 f3
X
7.48 = 26,264
Gallons per year

44. Calculating Storage
Charleston, West Virginia
October 2.67” Average Rain Fall – Average Low.
1000 sq. foot house X
2.67” rainfall (average monthly rainfall) /
12 (12 inches per cubic foot) =
222.5 cubic feet of water
250 (cubic feet) X
7.48 (7.48 gallons per cubic foot of water) =
1,664.3 gallons in January
1,664.3 / 4 = 416 gallons per family member
(family of 4)
416 / 30 (average days per month) = 13.9 gallons per day each

45. Calculating Storage
Charleston, West Virginia
July 4.95” Average Rain Fall – Average High.
1000 sq. foot house X
4.94” rainfall (average monthly rainfall) /
12 (12 inches per cubic foot) =
411.7 cubic feet of water
411.7 (cubic feet) X
7.48 (7.48 gallons per cubic foot of water) =
3,079.5 gallons in January
3,079.5 / 4 = 769.9 gallons per family member
(family of 4)
769.9 / 30 (average days per month) = 25.7 gallons per day each

46. Calculating Storage
Charleston, West Virginia
Average Water Use in the USA
Bath – A full tub is 36 gallons
Shower – New heads 2 gallons per minute / 5 gallons with the old
Brushing Teeth - < 1 gallon
Washing Hands & Face – 1 gallon
Face & Leg Shaving – 1 gallon
Dishwasher – 4 – 10 gallons per load
Dishwashing by Hand – 20 gallons
Clothes Washing – 25 gallons per load
Toilet Flushing – 1.6 – 3 gallons per flush
Drinking Water – 8 – 24 8oz cups per day
(1/8 – 3/8 gallon per day)
*A Santa Fe Family Uses 23 gallons Per Person Per Day For the Household

47. Calculating Storage
Charleston, West Virginia
Potable water at 2 gallons per day for family of 4 is 240
gallons per month – a 500 gallon tank sufficient
For whole house would suggest at least 2,ooo gallons –
67 gallon per day

48. Pumps:
Choose the right
one for the job

49. Pump Characteristics
 Water pumps are designed to push water not pull
 Whenever possible locate pumps so water flows into the pump
by gravity - Foot Valve
 Suction Head is the pressure required to pull water into the
pump housing, most pump not more than 10 feet
 Match needed flow rate with pump output GPM
 Sprinklers or flood irrigation uses much more GPM than Drip
Irrigation
 Prescreen to 1/8” for inlet of pump

50. Pressure Tank or On Demand
Pump
Pressure tank keeps extra water available so small
demands do not trigger pump start
 Prolongs the life of a pump by reducing on/off
 Provides water that is under pressure
On Demand Pumps-cycles on/off as
demand requires
- Does not require a pressure tank
- May have built in dry protection
- Usually has shorter life

51. Pump Controls
 Floats for On, Off & Auto Filling
 Pressure Switches
 Irrigation Computer
 Smart Controllers

52. Gutters
 Materials - Vinyl, Aluminum, Steel, Stainless, Copper
 Slope – 1/16” per 1’ to 1/16” per 10’
 Tilt Out – ½” to prevent water seeping into walls
 Expansion Joints for runs over 40’
 Sufficient Support
 Downspouts – 1 per 1,000 sq ft surface
 1 sq inch of outlet per 100 sq ft surface
 Screen to reduce debris entering conveyance
 Prune Branches
 Snow Cleats – reduce damage, increase catchment

53. On Ground Catchment
 Catch Boxes
 Drain Grates
 Patio Drains

54. Preventative Care & Health Risk
Realities
 Keep vegetation and animal nests away from the
catchment surface - First Flush Diverters
 Leaf Screens – make them accessible
 Good Things – Water improves with age –Biofilm Many
people around the world live on rainwater.
 Dilution reduces load on immune system
 Simple & Economical Filters Available

55. Sanitation
 Be cautious but not paranoid, filter for needs
 Don’t clean your tanks unless emergency-Biofilm
 Pollutants that can be found in rainwater:
 Microbiological: Parasites, Bacteria, Fungi, Organic - Bird
Droppings, Insects – UV Sterilization
 Chemical Contaminants: Volatile Organic Chemicals (VOCs) –
Solvents – Carbon Filter
 Synthetic Organic Chemicals: Usually only around heavy
industrial areas – Carbon Filter
 Minerals/Metals: Copper, Lead from roofs or gutters -

56. Sanitation: Microbes
 Viruses: smallest 20 to ~100 nanometers in size. Most difficult to
remove
 Bacteria: larger (0.5 to 3 micrometers) also can not be removed
by plain sedimentation or settling
 Protozoan: next largest (3 to 30 micrometers) largest ones likely
to gravity settle at appreciable rates. Can filter out some
 waterborne pathogens are often associated with larger particles
or they are aggregated (clumped). Aggregated or particleassociated microbes are easier to remove by physical processes
 Coagulation-flocculation
WHO 2012

57. Treatment of Stored Rainwater
 If going to do it, do it right
 Chlorination
 Filters
 Boiling
 Sunlight
 Additional Treatments

58. Chlorination
 Effective, but conduct with care
 Shock with 1 Tablespoon (.5 ounce or 14g) swimming pool calcium
hypochlorite (60-70%) per 530 gallons (2000 liters)
 Stir and let stand 24 hrs for chlorine to dissipate
 Maintain with 1/7th of the above amount - stir in and let stand 2 hrs
 Mix chlorine into water NOT water into chlorine
webelements

59. Filters
Sediment/Screen 80-100
micron
Carbon – Best for VOC’s
Whole house 10 micron can be
found for $200
Ceramic – for smaller particles –
viruses
Reverse Osmosis (RO)
Finest yet wastes 1-5 x filtered

60. Sand Filter
“Biofilm” provides
the effective
purification in
potable water
treatment with 9099% bacterial
reduction
Courtesy of Clean Water for Haiti & National Drinking Water Clearing House

61. Filtration - Ceramic
The Gravidyn is a microporous ceramic filter
element with an inner core filled
with activated carbon granulate.
99.9999 % removal of harmful Bacteria and
Parasites 99.99 % removal of
Cryptosporidium and Giardia
General: Removal of organics (this will include:
organic contaminants,
pesticides, micropollutants, humic acids,
detergents) and free chlorine
Katadyn Ceramic Filtration System
$295.00 - $318.00 www.katadyn.com

62. Sanitation
Viruses: 99.999% reduction MS2 - Fr
Coliphage*Exceeds purification
standards Pathogenic Bacteria, Parasites,
and Cysts
100% reductionE. coli, Klebsiellaterrigena,
Pseudomonas aeruginosa, Giardia,
Cryptosporidium*Exceeds purification
standards Trihalomethanes: Removed to
below detectable limits - 99.99999%
reduction Bromodichloromethane,
Bromofore, Chloroform,
Dibromochloromethane
Berkey Filtration System
$228.00 - $625.00www.berkeyfilters.com

63. Sanitation
Katadyn Hiking Carbon System
$50.00 - $150.00

64. Boiling
 2-3 minutes
 A lot of fuel
 Take a while to cool
 Not always feasible
 Solar Cookers
Dr. Kundapur

65. Low-Tec Sedimentation
 Simple and low cost: storage vessels - pots, buckets
 Clays and smaller microbes do not settle
 Do not disturb sediment particles at bottom
 Unreliable to reduce pathogens
 Remove solids and clean regardless of storage vessel type
 Good pre-treatment to remove turbidity before UV or
chemical disinfection

66. S.O.D.I.S.
Solar Disinfection
6 hrs full sun – UV starilization

67. Sequence
Combining Filtration and
Purification Strategies for
Potable Water

68. Sequence
Combining Filtration and
Purification Strategies for
Potable Water

69. Corrosion Control
 pH Rainwater naturally Acidic:
4.5-6.3 – usually not a problem
 Affects Copper – raise with
Baking Soda (sodium
bicarbonate) periodically to pH
of 7.4
 In-line Filters Available – Calcium
carbonate (limestone) pellets,
Sodium oxide (lime) pellets –
these must be downstream of
UV units

70. Water Quality Enhancers
 Calmed Inlets – Minimize the disturbance of sediment on
bottom of tank and Biofilm
 Floating Valve Out-take – Remove water from the “sweet
spot” when possible

71. Thank You!
Jeremiah Kidd
San Isidro Permaculture
jeremiah@sipermaculture.com
www.sipermaculture.com
+1 (505) 983-3841

72. Thanks to
 Aaron Kauffman
 Brad Lancaster
 Chelsea Green Publishers
 John Gould & Erik Nissen - Peterson

73. Resources

Rainwater Harvesting for Drylandswww.HarvestingRainwater.com

Virginia Rainwater Catchment
Manualhttp://www.cabellbrandcenter.org/Downloads/RWH_Manual2009.pdf

Simple explanation and diagram http://www.chelseagreen.com/content/free-yourwater-fundamentals-of-a-rainwater-harvesting-system/

Supplier in Salem, Virginia http://rainwatermanagement.com

Supplier in Maryland offers all parts needed for a
systemhttp://www.conservationtechnology.com

Supplier in Georgia http://www.rainharvest.com

Contech Engineered Solutions 700 Tech Dr, Winchester, KYwww.conteches.com

First Flush Design
http://cals.arizona.edu/cochise/waterwise/first_flush_diverters.pdf