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Community Water

Community Water Monitoring in the US

The U.S. Environmental Protection Agency (EPA) requires community water systems to provide drinking water that meets standards established under the Safe Drinking Water Act. EPA establishes drinking water standards for individual contaminants and groups of contaminants. Typically, EPA establishes Maximum Contaminant Levels (MCL) for contaminants and sets up requirements for making sure water systems follow the regulations. When a contaminant in drinking water cannot be measured feasibly, EPA establishes drinking water Treatment Technique Requirements (TTR) based on indicators of water quality. Also, EPA sets requirements about the treatment required and ways to measure how well the treatment processes work. Drinking water meets current public health standards when it complies with MCLs and TTRs.

Every year, community water suppliers send customers a Consumer Confidence Report which contains information about the quality of water. It includes information on

  • where the water comes from,
  • how it is treated,
  • the chemicals they test for, and
  • the highest concentration of each of those chemicals that they found in the past year.

If you did not receive a Consumer Confidence Report you can get one by contacting your water supplier.

When a problem that might pose a health risk is discovered in a water system, the supplier is required to notify its customers. The most common problems are water quality violations and treatment technique violations. Water quality violations happen when contaminant levels exceed health standards. Treatment technique violations involve malfunctions in the water treatment system.

If the problem is serious, the water system supplier must notify the public within 24 hours. For less serious problems they must notify the public within 30 days. In some cases, water system suppliers must work with the state drinking water program to prevent a more serious problem, even if no violation has occurred.

When a community water system supplier notifies its customers that a problem has occurred, customers should follow carefully the advice given by the supplier and the local public health officials. If you think your drinking water is contaminated, call your water supplier or state drinking water program. You can locate these agencies or find information on drinking water in general from EPA's Safe Drinking Water Hotline at (800) 426-4791.

Drinking water standards and monitoring requirements change often. EPA may add contaminants to the list of those currently regulated. Also, EPA periodically must review and, if necessary, revise existing regulations. Revisions are made when new information is available about health effects, treatment, analytical methods, and contaminant occurrence. Each community water contaminant has its own monitoring requirements set by EPA. These requirements are outlined in EPA’s Standardized Monitoring Framework. Requirements are listed for groups of contaminants in broad categories rather than by name. Categories include inorganic contaminants (IOCs), synthetic organic contaminants (SOCs), volatile organic contaminants (VOCs), and radionuclides.

Category Tracking Network Contaminants
Inorganic Contaminants (IOCs) arsenic
Synthetic Organic Contaminants (SOCs) atrazine, di(2-ethylhexyl) phthalate
Volatile Organic Contaminants (VOCs) perchloroethene, trichloroethene
Radionuclides radium, uranium

Nitrate is an IOC but it has special monitoring requirements. Disinfection by-products are in their own category.

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