2. ● Boiling water in a carved
out burl of wood with
plants such as water lily,
water poppy,sweet flag,
and club rush.
Native American Water Treatment
Techniques
d
ddd
Carved out logs were used to insert
hot rocks into the water along with
coals from the wood to sterlize the
water for drinking.
3. Water supply technologies such as dug wells and
the use of wooden and lead pipes were the rule. Water and wind powered mills provided the
power source for anything that could not be accomplished with hand tools.
Early American Colonies
All of the early colonies were coastal and situated around
a water source such as a spring, creek or river.
Although there were not communal treatment plants until
the 1800s, distribution systems were in place in a few
colonies such as the ‘conduit’ in Boston that was set up to
provide drinking water as well as fire suppression supply to
the homes of those who financed the project.
Since the costs were fairly high and government was not required to provide running water to homes, the vast majority
of early water systems were completely private systems that only the more affluent members of the community could
afford to have running water.
4.
5. In 1804 First municipal water filtration works opens in Scotland. It used slow sand filtration to try and purify water.
Chlorine was used by British scientist John Snow in 1854 to disinfect water from a well he linked to a cholera
epidemic.
In 1896 the Louisville Water Company innovates a new treatment technique by combining coagulation with rapid-
sand filtration.
For most of the 19th century, water providers were primarily concerned with where the supply came from and
hence the majority of construction projects were canals and replacing older wooden pipes with cast iron ones that
could hold under much higher pressures.
Growing population and water demand required greater cooperation between agencies and in response to this
organizations such as the AWWA (American Water Works Association) and NEWWA (New England Water Works
Association)
Water in the 1800s
6. Slow sand filters work through the formation of a gelatinous layer
(or biofilm) called Schmutzdecke in the top few millimetres of the
fine sand layer. The Schmutzdecke is formed in the first 10–20
days of operation.
As a Schmutzdecke ages, more algae tend to
develop and larger aquatic organisms may be present including
some bryozoa, snails and Annelid worms. The Schmutzdecke is
the layer that provides the effective purification in potable water
treatment, the underlying sand providing the support medium for
this biological treatment layer. As water passes through the
Schmutzdecke, particles of foreign matter are trapped in the
mucilaginous matrix and dissolved organic material is adsorbed
and metabolised. The water produced from a well-managed slow
sand filter can be of exceptionally good quality with 90-99%
bacterial reduction
Rapid sand filters use relatively coarse sand and other granular media to remove particles
and impurities that have been trapped in a floc through the use of flocculation chemicals.
The unfiltered water flows through the filter medium under gravity or under pumped
pressure and the floc material is trapped in the sand matrix.
Mixing, flocculation and sedimentation processes are typical treatment stages that precede
filtration. Chemical additives, such as coagulants, are often used in conjunction with the
filtration system.
The two types of rapid sand filter are the gravity type (e.g. Paterson's filter) and pressure
type (e.g. Candy's filter).
A disinfection system (typically using chlorine or ozone) is commonly used following
filtration. Rapid sand filtration has very little effect on taste and smell and dissolved
impurities of drinking water, unless activated carbon is included in the filter medium.
Rapid sand filters must be cleaned frequently, often several times a day, by backwashing,
which involves reversing the direction of the water and adding compressed air. During
backwashing, the bed is fluidized and care must be taken not to wash away the media.
7. With germ theory thoroughly established by the turn of the 20th century most water providers put
a high priority on protection of public health.
In 1908, chlorine was used for the first time as a primary disinfectant of drinking water in
Jersey City, New Jersey. The use of other disinfectants such as ozone also began in Europe
around this time, but were not employed in the U.S. until several decades later.
Congress passed the Public Health Service Act in 1912 which authorizes surveys and
studies for water pollution, particularly as it affects human health.
The first standards were set by the PHSA that define maximum contaminant limits for
drinking water but only applied to water that was travelling between states.
The drinking water standards did not apply for municipal drinking water until the 1940s
Early 1900s
8. In 1972, the Clean Water Act was passed in the United States
The objective of the Federal Water Pollution Control Act, commonly referred to as the Clean Water Act (CWA), is to
restore and maintain the chemical, physical, and biological integrity of the nation's waters by preventing point and nonpoint
pollution sources, providing assistance to publicly owned treatment works for the improvement of wastewater treatment, and
maintaining the integrity of wetlands.
In 1974 the Safe Drinking Water Act (SDWA) was formulated.
The SDWA requires EPA to establish National Primary Drinking Water Regulations (NPDWRs) for contaminants that
may cause adverse public health effects.[8]
The regulations include both mandatory levels (Maximum Contaminant Levels, or MCLs) and nonenforceable health goals
(Maximum Contaminant Level Goals, or MCLGs) for each included contaminant. MCLs have additional significance
because they can be used under the Superfund law as "Applicable or Relevant and Appropriate Requirements" in cleanups
of contaminated sites on the National Priorities List.
Late 1900s to present
