Water Resources of the United States

Water used in homes, schools, businesses, and industries must be cleaned or treated before it can be used again or returned to the environment. No matter where you live, in an urban or rural setting., the water you use does not just disappear: it is piped to a treatment system. President George Bush and the US, Congress proclaimed 1992 the Year of Clean Water. The treatment of wastewater is important to keeping our water clean. This poster depicts what happens to the water we all use, and how wastewater is treated so that it can be used again. The poster is folded into 8 1/2- by 11-inch panels; front and back panels can easily be photocopied. A black and white version is available for coloring by younger children.

Drawings on the left-hand side of the poster represent the large city (urban and suburban areas) and drawings on the right-hand side of the poster represent small towns and rural areas. In the city, the used water is piped through large underground sewer pipes to a community wastewater-treatment facility. At the wastewater-treatment facility, the wastewater is treated by various processes, which include grit chambers, sedimentation tanks, trickling filters, and disinfection. The treated water then is reused or returned to the environment.

In small towns and rural areas, several alternative and individual onsite collection and treatment processes are used in treating wastewater. This poster depicts several processes, which are: lagoons, wetlands, septic tanks and leach fields, and sand filters.

This poster is the second in a series of Water Education Posters designed to stimulate students' interest in water resources. Posters in the series can be joined to create a large wall mural, Please see the Acknowledgments section for more information.

	Septic Tank The septic tank separates solids from liquids. The solids (sludge) collect on the bottom of the tank and are periodically pumped out and disposed of at a community treatment facility or an approved disposal site. The partially treated wastewater is piped to a leach field.
	Leach Field Wastewater from the septic tank is piped to the leach field or absorption field and seeps through the soil. The soil serves as a filter, removing bacteria and nutrients from the wastewater. The wastewater is purified by the microorganisms that live in the soil.
	Sand Filter A system used in areas with high water tables, shallow soils, or soils that water cannot flow through easily. Sand and gravel are mounded on top of natural soil to filter wastewater received from the septic tank before the wastewater reaches natural soil.
	Lagoon A treatment pond, usually 1 to 1.5 meters deep, that uses sun algae, microorganisms, and oxygen to remove organic matter and nutrients from wastewater. The resultant wastewater may be disinfected by chlorine before being reused or released to the environment.