Make a list of the ways you have used water today. If you think about it carefully, it should be a long list. Food production, washing, drinking, industry, all these and more depend upon water. Did you ever wonder where your drinking water comes from? When you turn the handle, what has already happened to make that water drinkable? This page has information on: water treatment, making a model of a water filter, the importance of waste water treatment, and links to information on water and water conservation.
Here is a diagram of a typical water treatment system. If you have "city water," the system of pipes which leads to your house or apartment starts at 1 on the diagram, a lake, river, or well. On the diagram, 2 is a pump station or house which moves water from the source to a treatment plant. Inside the plant, the water gets a pre-treatment of alum and chlorine. At 3, the mud and other stuff that clumps together because of the alum, settles out of the water and is gathered at 4 and removed from the treatment plant. At 5, the water goes through layers of charcoal or anthracite, sand, and then gravel. This filters out any small pieces of material still in the water. At 6, fluoride, chlorine and lime or phosphate are added as post-treatment. Finally, the water moves on to storage in a water tower at 7. Finally, the water moves through water mains to houses and businesses (shown as 8).
Click here for information on How Water Towers Work.
Purifying water requires aerating it, adding chemicals so solids clump (coagulate), sedimentation so solids drop out, filtration, and disinfection with chemicals. At which numbers on the diagram do these steps happen?
You can make a model of how the filtering system of a water treatment plant works. Cut the top from a plastic soda pop bottle and hold it upside down like a deep funnel. Put cotton in the neck of the bottle and then a layer of fine sand, a layer of activated charcoal (from a drugstore), then coarse sand, then fine sand, and, on top, coarse gravel. Pour some muddy water through the layers and see how it comes out the bottom.
Remember, this does not take care of microscopic organisms which could make a person sick. These are usually killed by adding a chemical like chlorine. For information about waterborne and other diseases, visit the Massachusetts Water Resources Authority.
After you use water in your home it goes to a wastewater treatment plant before going back into a river or lake. Find out about this process. For information on dealing with wastewater, visit the Environmental Protection Agency's (EPA) Wastewater Management site.
Visit a pond or stream. Use a strainer or net to scoop into the mud in the bottom or turn over rocks to see some of the insects and other small creatures which live there. What would happen to these if untreated wastewater was added to the pond or stream?
The USGS has a nice page about the water cycle. You and the water you use are part of a watershed. Or visit the Watershed Education Resources page. The EPA has a water issues site called "What's Up With Our Nation's Waters?"
We usually have plenty of water here in the humid eastern states, but water conservation can be important in arid parts of the country, during dry years, and to make sure we don't put more wastewater into the system than can be treated. For more curriculum materials, visit Educating Young People About Water and Water Science for Schools. The Iowa Project WET site has a number of other water links.