The United States has one of the safest water supplies in the world. Over 90 percent of Americans get their tap water from community water systems, which are subject to safe drinking water standards.
Drinking water quality varies from place to place, depending on the condition of the source water from which it is drawn and the treatment it receives, but it must meet U.S. Environmental Protection Agency (EPA) regulations. Community water systems follow the rules set forth by the Safe Drinking Water Act (SDWA).external icon Many states enforce their own drinking water standards that are at least as protective as EPA’s national standards. The SDWA rules include guidelines for drinking water quality, water testing schedules, and water testing methods.
Even though U.S. tap water supplies are considered to be among the safest in the world, water contamination can still occur. There are many possible sources of contamination, including:
- Sewage releases
- Naturally occurring chemicals and minerals (for example, arsenic, radon, uranium)
- Local land use practices (for example, fertilizers, pesticides, livestock, concentrated feeding operations)
- Manufacturing processes (for example, heavy metals, cyanide)
- Malfunctioning on-site wastewater treatment systems (for example, septic systems)
In addition, drinking water that is not properly treated or that travels through an improperly maintained distribution system (pipes) may also create conditions that increase risk of contamination.
Private wells, which are not regulated by the EPA, supply drinking water to over 15 million homes. Well owners are responsible for keeping their water clean and safe. Visit CDC’s Private Wells page for more information on water quality of private ground water wells.
When water system officials find an issue with the drinking water supply (for example, that it has become contaminated), a water advisory may be issued to help protect the public’s health.
The presence of certain contaminants in our water can lead to health issues, including gastrointestinal illness, reproductive problems, and neurological disorders. Infants, young children, pregnant women, the elderly, and people with weakened immune systems may be especially at risk for illness.
The EPA sets standards and regulations for the presence and levels of over 90 contaminants in public drinking water, including E.coli, Salmonella, Cryptosporidium, metals such as lead, and disinfection byproducts. Learn more about these germs in the Diseases and Contaminants page.
Every community water supplier must provide an annual report, sometimes called a Consumer Confidence Report, or “CCR,” to its customers. The report provides information on local drinking water quality, including the water’s source, contaminants found in the water, and how consumers can get involved in protecting drinking water.