PWSs must provide their customers with a water quality report, also called a Consumer Confidence Report, every year. The CCR contains water quality information based on official laboratory analyses of the water from the previous year. Learn more here: (English / Español).

PWSs must monitor the quality of the water they provide to consumers by testing the water using samples of their water sources, like lakes for surface water sources or aquifers for groundwater sources. These samples are sent to an official lab and tested for contaminants that are regulated by the state and federal governments.

If the test results show that regulated contaminants are not present in the water or are at levels under what is considered safe, by law, the PWS is in compliance with the law. However, if the test results show any regulated contaminant is present in the water at levels above what is considered safe, by law, the PWS has violated the law.

Depending on the severity of the violation and which contaminant is involved, the PWS must follow different protocols. More about monitoring and regulated contaminants, here: (English / Español). More about the levels at which contaminants are considered to be safe if present in drinking water, here: Maximum Contaminant Levels.

Information about specific categories of contaminants:

• Inorganic and Organic Chemical Contaminants (English / Español)

• Bacteria (English / Español)

• Radioactive Contaminants (English / Español)

• Secondary Contaminants (English / Español)

A PWS may need to treat water to make it safe and healthy for human consumption. Common treatment methods include fluoridation and disinfection using chlorine. Fluoridation is the process of adding fluoride to drinking water in order to protect consumers’ dental health.1 Disinfectants, like chlorine, are added to water to make bacteria and other disease-catching microorganisms inactive. More about treating drinking water for contaminants, here: (English / Español).

If the water is overtreated, or disinfection byproducts or disinfectant residuals enter the water at acute levels the system can expose residents to unsafe drinking water. Learn more, here: (English / Español).

The quality and safety of drinking water can also change as it moves through pipes, tanks, and other structures to get to a consumer’s location. Those pipes, tanks, and other structures are also known as the water system’s “water distribution system” because it is through these structures that the drinking water is distributed to the consumer. Thus, it is also crucial for  a PWS to ensure this distribution system does not render treated water unsafe for consumption. More information, here: (English / Español).

A public notice (notice) is a document that a public water system must send out to their consumers if they detect that their drinking water supply is unsafe – usually when the amount of a contaminant in the water is higher than what is legally allowed. The notice is meant to inform consumers of the drinking water risks and explain to consumers how to respond. The appropriate response depends on the type and level of risk. More information, here: (English / Español).

A water shortage emergency occurs if the ordinary demand for water in the system cannot be met without depleting the water supply to the point where there would be insufficient water for human consumption, sanitation, and fire protection.2 In these situations, a PWS must declare a water shortage emergency, and adopt regulations and restrictions on the delivery and use of water. More information, here: (English / Español).

There are requirements to keep certain physical and electronic documents pertaining to a PWS on or at a convenient location near the PWS. The length of time depends on the type of document, such as copies of public notices issued or records of contaminant analyses. More information, here: (English / Español).