Name: _______________________________________________________________
Water Sanitation Activity
While nearly 70 percent of the world is covered by water, only 2.5 percent of it is fresh. The rest is
saline and ocean-based. Even then, less than 1 percent is drinkable. Community water systems get
their water from two sources: surface water and ground water. People use surface and ground water
every day for a variety of purposes, including drinking, cooking, and basic hygiene, in addition to
recreational, agricultural, and industrial activities. According to the United States Environmental
Protection Agency (EPA), the majority of public water systems are supplied by ground water; however,
more persons are supplied year-round by community water systems that use surface water. This is
because large, well-populated metropolitan areas tend to rely on surface water supplies, whereas small,
rural areas tend to rely on ground water.
Surface Water - Surface water
is water that collects on the
ground or in a stream, river, lake,
reservoir, or ocean. Surface
water is constantly replenished
through precipitation, and lost
through evaporation and seepage
into ground water supplies.
According to the EPA, 68% of
community water system users
received their water from a
surface water source, such as a
lake.
Ground Water - Ground water, which is obtained by drilling wells, is water located below the ground
surface in pores and spaces in the rock, and is used by approximately 78% of community water systems
in the United States, supplying drinking water to 32% of community water system users. EPA also
estimates that approximately 15% of the U.S. population relies on private ground water wells.
Source Water Protection
The Safe Drinking Water Act (SDWA) was originally passed by Congress in 1974 to protect public health
by regulating the nation's public drinking water supply. The law requires many actions to protect
drinking water and its sources: rivers, lakes, reservoirs, springs, and ground water wells. Even though
most community drinking water (especially from surface water sources) is treated before entering the
home, the cost of this treatment and the risks to public health can be reduced by protecting source
water from contamination. We all live in a watershed, which is an area that drains to a common
waterway such as a stream, lake, wetland, or ocean. The EPA and many other organizations collaborate
with communities to work toward protecting watersheds.
Pollutants enter the water environment from two main types of sources.
Point sources: A point source is a single, identifiable source of pollution, such as a pipe or a drain.
Industrial wastes are commonly discharged to rivers and the sea in this way. High risk point source
waste discharges are regulated by EPA through the works approval and licensing system, and
associated compliance and enforcement activities.
Nonpoint sources: Nonpoint source (NPS) pollution, unlike pollution from industrial and sewage
treatment plants, comes from many sources. NPS pollution is caused by rainfall or snowmelt moving
over and through the ground. As the runoff moves, it picks up and carries away natural and humanmade pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters and ground waters.
Non-point source pollution is often more difficult to control than point source pollution.
Name: _______________________________________________________________
Some examples of nonpoint source pollution are:
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Urban land use: Storm water from street surfaces is often contaminated with car oil, dust and
the feces of animals and soil and sediment run-off from construction sites, and in industrial
areas often contains more toxicants and chemicals.
Agricultural land use: In farming areas non-point sources of pollution include pesticides,
fertilizers, animal manure and soil washed into streams in rainfall run-off. Nutrients are one of
the top main polluters of ground water.
Forestry land use: Forestry operations may contribute to non-point source pollution of
streams by increasing soil erosion and sediment run-off.
Drinking Water Treatment Process
In general, the treatment of drinking water by municipal water systems involves a few key steps:
1. Aeration: The water is mixed to free dissolved gases and to suspended particles in the water
column.
2. Flocculation: The materials and particles present in drinking water (clay, organic material,
metals, microorganisms) are often quite small and so will not settle out from the water column
without assistance. To help the settling process along, "coagulating" compounds are added to
the water, and suspended particles "stick" to these compounds and create large and heavy
clumps of material.
3. Sedimentation: The water is left undisturbed to allow the heavy clumps of particles and
coagulants to settle out.
4. Filtration: The water is run through a series of filters which trap and remove particles still
remaining in the water column. Typically, beds of sand or charcoal are used to accomplish this
task.
5. Disinfection: The water, now largely free of particles and microorganisms, is treated to
destroy any remaining disease-causing pathogens. This is commonly done with chlorination (the
same process used to eliminate pathogens in swimming pools), ozone, or ultraviolet radiation.
The water is now safe to drink and is sent to pumping stations for distribution to homes and
businesses
Activity: Simulated Drinking Water Treatment Plant
In this activity we’ll be treating "contaminated" water to observe firsthand the steps involved in
purifying water for human consumption. The activity will use everyday items to carry out the steps in
drinking water treatment and you will record changes in the water’s properties as the process
progresses.
*Turbidity describes the clarity or “muddiness” of a water sample and is measured by examining the
transmission of light through a water sample.
WARNING: The water used in the experiment is not suitable for drinking at any stage in
treatment. Hence, do not consume the water under any circumstances.
Step 1: Contaminate your water. Each group is to get a water sample from the teacher and then choose
two “contaminants” you would like to add to your water. Cap and shake the container of contaminated
water, and pour it into one of the empty cups. Pour the water into one of the cups, and then pour the
water back and forth between the cups five times (First step of filtration is aeration).
Appearance:
Odor:
Turbidity:
Name: _______________________________________________________________
Point Source Contaminants:
Non-point Source Contaminants:
Step 2: Coagulation
The water should be in one of the cups. Add 2 tablespoons of alum crystals to the container and stir
gently for 4 minutes. The alum will act as a coagulant and bind with the particles suspended in the
water.
Appearance:
Odor:
Turbidity:
Step 3: Sedimentation
Leave the container undisturbed for 15 minutes, and record observations of the water's appearance at 5
minute intervals.
5 minutes
10 minutes
15 minutes
Appearance:
Odor:
Turbidity:
Step 4: Filtration
Use the filtration device made by your teacher to carefully (and I mean carefully) and slowly pour off
the top two-thirds of the water in the container into a clean cup. It is important that you do not disturb
the sediment when pouring, so take a great deal of care during this step. Allow the water to settle, and
then pour the water from the cup into the filter apparatus. The water will filter through the sand and
pebbles and collect in the beaker beneath the apparatus.
Appearance:
Odor:
Turbidity:
Name: _______________________________________________________________
Filtering Apparatus Diagram
(Students draw this here while
waiting for the timer)----------------------------
Step 5: Disinfection
The final step in the process, the elimination of any
remaining microorganisms will not be done in this exercise.
This is normally an important step in the process, but as the
water is not to be consumed and disinfection methods can be
dangerous outside of controlled conditions, this step will not
be done in this exercise.
Lab Questions
1. Name one way that human population
can affect our water quality.
3. Name one way our use of resources can
affect our water quality.
2. Name one way our food industry can
affect our water quality.
4. Name one way nature can affect our
water quality.
5. What step do you feel is most effective? Why?
Name: _______________________________________________________________
Teacher Notes (do not print)
Constructing the Filtering Apparatus – Done by the teacher!
The activity requires the construction of an apparatus for filtering the water sample. Directions for
constructing the apparatus and a complete list of materials are provided below.
(1.) Obtain a plastic two-liter soda bottle with the bottom removed.
(2.) Secure a coffee filter to the neck of the bottle with a rubber band.
(3.) Turn the bottle upside down and secure it in place as described by your instructor.
(4.) Gently add 400 ml of pebbles to the bottle. Make sure the pebbles do not puncture the coffee filter.
(5.) Gently add 800 ml of coarse sand on top of the pebbles. Avoid shaking the bottle whenever
possible.
(6.) Gently add 800 ml of fine sand on top of the coarse sand. Again, avoid shaking.
(7.) Place a clean 500 ml beaker beneath the inverted neck of the bottle to collect the water from the
apparatus.
(8.) Clean the sand and pebbles by slowly pouring 5 liters of clean tap water (in 400 ml increments to
avoid overflowing the beaker) through the apparatus. Take steps to minimize the disturbance to the
uppermost sand layer as you pour.
(9.) Once the flushing of the filtering apparatus is complete, thoroughly rinse the collection beaker with
tap water and return it to its place beneath the bottle. Your apparatus is now complete and ready for
use.
For each station, the following materials are required:
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Teacher made pre-contaminated water (water, dirt, sand)
Contaminants: motor oil, grass, fish food, food coloring, conditioner
1 two-liter plastic soda bottle, with bottom removed (like a funnel)
2 Clear large cups
20 grams alum (potassium aluminum sulfate), approximately 2 tablespoons
fine sand
coarse sand
small pebbles
500 ml (or larger) beaker
1 coffee filter
1 rubber band
1 tablespoon for alum
1 stopwatch (clock in room may substitute)
For a class of 30 (with 3 students in each group) – 10 kits should be made
Movie of the process if needed: http://www.epa.gov/safewater/kids/flash/flash_filtration.html