Water Sources

Where Your Tap Water Comes From

Most U.S. tap water comes from surface or ground water

Source water refers to bodies of water (such as rivers, streams, lakes, reservoirs, springs, and ground water) that provide water to public drinking-water supplies and private wells. Water sources can include:

In the United States, 9 out of 10 people get their water from one of more than 148,000 public water systemsexternal icon. To make sure water from these systems is safe to drink, federal, state, and local authorities regulate and monitor public water systems.

How do I know my water is safe?
Customers who are served by a public water system can contact their local water supplier and ask for information on germs and chemicals in their drinking water. Customers are encouraged to request a copy of their Consumer Confidence Report.

People who use private wells or cisterns should have their water tested annually for germs and chemicals to ensure their drinking water is safe.

The water flowing from your tap may come from hundreds of miles away. Public water systems are most often supplied by surface water or ground water. Large cities and towns usually get their water from surface water supplies or a mix of surface and ground water supplies. Some small, rural communities rely solely on ground water supplies, which may or may not require treatment to meet drinking water standards.

If you do not get your water from a public water system, you most likely have a private ground water well. Around 13 million U.S. householdsexternal icon get their drinking water from a private well.

If your home is not connected to a public water system and you do not have a ground water source, you may get your water from a rainwater collection system. In many areas of the world, people collect and use rainwater as their drinking water source.

Illustrating difference between surface water (lake) and ground water (under the ground)

Ground water

Ground water is located below the surface of the earth in spaces between rock and soil. Ground water is naturally filtered, which might remove some germs and chemicals depending on the water’s depth and the area’s local geology. Water that comes from a well is ground water and might receive some level of treatment before it reaches your tap.

Surface water

Surface water collects on the ground or in a stream, river, lake, reservoir, or ocean. Surface water is constantly evaporating out of water bodies, seeping into ground water supplies, and being replenished by rain and snow. A springexternal icon is where ground water comes to the surface and becomes surface water. Public drinking water systems that use water from streams, rivers, lakes, or reservoirs treat the water before it reaches your tap.

Protecting source water makes tap water safer

We all live in a watershedexternal icon—the land area that drains to a common waterway such as a stream, lake, wetland, or ocean. Land use, local ecologies, and other watershed conditions affect the quality and amount of water in rivers, lakes, and other sources of water. Protecting sources of water and watersheds from contamination reduces the risk of unsafe levels of germs or chemicals in your water and the cost of water treatment. Protecting water sources and watersheds from contaminants—such as our waste and germs and chemicals from industrial and commercial processes—also provides additional benefitsexternal icon to the communities of people and wildlife that live there.

The U.S. Environmental Protection Agencyexternal icon (EPA), U.S. Geological Surveyexternal icon (USGS), National Park Serviceexternal icon, and many state and local organizations work with communities to protect watersheds.

Visit EPA’s website to learn more about your local watershed and what you can do to protect your source water: