After drinking water is treated and meets the U. American water distribution systems span nearly 1 million miles and deliver water to approximately million people.
Distribution systems are mostly underground and include pipes, control valves, pumps, meters, storage tanks, and hydrants. Distribution systems must provide an adequate amount of water, and they must also provide it with sufficient pressure. Without pressure, water stands still. Water pressure is created by pumping water to the top of a water tower or to a water tank in a high location.
When the water descends, it creates force, which in turn moves the water through the mains and pipes. Residential water pressure is usually kept between 45 and 80 pounds per square inch psi. The pipes that transport water can be made of several different materials. Some of the most common materials include:. An alloy of iron and carbon, steel is the strongest and most durable material used for water supply pipes.
These pipes have a protective zinc coating to prevent rusting. Once popular, the use of these materials is declining because pipes corrode over time, giving water an unpleasant taste and smell. This iron alloy has been used for water distribution pipes for hundreds of years. Concrete cement pipes are still used and tend to be resistant to erosion. 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. EPA and many other organizations collaborate with communities to work toward protecting watersheds External. Top of Page.
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CDC is not responsible for Section compliance accessibility on other federal or private website. The U. Drinking water sources in California are groundwater , the Central Valley Project , local streams and reservoirs, the State Water Project or some independent water projects in populous cities. There is increased attention to accessing water from nontraditional sources, such as desalinated seawater, brackish groundwater and highly treated wastewater that is used for indirect potable reuse.
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