America has some of the safest drinking water in the world. The United States Environmental Protection Agency protects drinking water by federal law, knows as the Safe Drinking Water Act (SDWA). The SDWA ensures measures are in place to safeguard drinking water and that they meet or exceed the water quality standards required for public safety. All public water systems mandated to follow the Safe Drinking Water Act can be privately or publicly owned. Currently, there are over 170,000 public water systems in the United States.

First passed in 1974, Congress instituted the SDWA to protect public health from municipal drinking water supplies. Laws pertaining to the SDWA protect the public from both man-made contaminants, in addition to naturally occurring constituents. When first enacted, the SDWA emphasized only the treatment (cleaning) of the water as means to protect public health. However, in 1996 the SDWA was amended and now includes a wide range of methods expanding the requirements to provide safe drinking water to customers. These means include inclusion of water treatment operator training, source water protection, providing funding for infrastructure improvements, as well as providing information to the public relating to water quality.

The law protects not only the drinking water end product, but also the sources (where drinking water comes from) of water including: rivers, lakes, reservoirs, springs and groundwater wells, however it does not regulate private wells. Together the US EPA, each of the states, tribes and water agencies partner to protect drinking water throughout the country. Most of the supervision of these regulations is handled at the state level. At the local level, each public water system must remain within the standards.

Scientific testing is required on a daily or monthly basis to test for contaminants. If water testing proves that water quality is not within allowable limits, water agencies are required to notify customers immediately. Each year, the Safe Drinking Water Act requires that public water agencies produce a consumer confidence report, also known as a water quality report. This report must be made available to all customers as required by law. The report contains information pertaining to contaminant levels found in drinking water, as well as the allowable limits for each of these constituents. Regulation is in place to protect against pollution to source water that can impact drinking water.

When setting regulations for tap water standards, the US EPA prioritizes contaminants, also called constituents, by risk and how often they are present in water supplies. In addition, a public health goal is in place to help assess risks to individuals with compromised immune systems (infants, children, child-bearing women, elderly, etc.) Contaminants found in water are reported and monitored. Drinking water standards are legally enforceable and if not followed, both the US EPA and the states can take action. The Safe Drinking Water Act maintains a nationwide standard to protect the integrity of tap water in the U