FAQs: Standards & Testing

How standards for water safety are set, what those standards mean, how they are enforced, and testing frequency

Frequently Asked Questions

Generally, how does Massachusetts drinking water compare to that of other states?

Every day, more than six million Bay Staters turn on the tap and take a drink of water from a public system. Some of those people worry that their water might not be safe. Considering how often they are exposed to news reports about water-borne illnesses and commercials on bottled water, that's understandable. Nevertheless, the public water supplies in Massachusetts are among the best in the country, and they are subject to the most stringent government standards in the world.

How safe is drinking water in Massachusetts?

Very safe. Both the US EPA and the MassDEP have very stringent standards to ensure that public drinking water is safe. MassDEP requires your local water supplier to perform ongoing tests for the presence of bacteria, lead, other heavy metals, herbicides, pesticides, and industrial solvents. If contaminants exceed the MCL standards, the water system is required to notify consumers through local newspapers or radio stations. If bacteria or chemicals pose a threat to public health, the water supply is treated to remove the contaminants or is taken out of service until a solution is found.

Who sets the standards for public drinking water? How often are they changed or updated?

US EPA develops national standards after extensive research and input from states, scientists, public water systems, and the general public. The federal Safe Drinking Water Act and its amendments were passed by the U.S. Congress to ensure all public drinking water meets public health standards. In Massachusetts, MassDEP is the agency authorized to ensure that all PWS meet the federal standards, such as testing for 80 contaminants in drinking water. States may choose to set stricter standards; however, all states must have standards at least as stringent as US EPA's. MassDEP's Office of Research and Standards develops guidelines for chemicals that do not have MCLs.

The U.S. Congress required US EPA to publish a list of contaminants that may require regulations every five years, starting in 1998. Every five years US EPA is required to decide whether or not to regulate five contaminants from the list based on adverse health effects, national occurrence, and several other factors.

What are the differences between an MCL (maximum contaminant level) and an MCLG (maximum contaminant level goal) in terms of public health?

MCLs are enforceable numerical limits that restrict the concentration of specific contaminants in the nation's drinking water. An MCLG is a non-enforceable goal derived solely from health effects data. An MCL is set as closely as possible to the MCLG, taking technology and costs into account.

How often is a local water system tested to ensure it complies with the standards?

PWSs must test all sources of water on a regular basis. Most systems test for over 80 contaminants as scheduled by MassDEP. The schedule depends on past testing results and the federal requirements. If a system detects a contaminant above the MCL, additional monitoring and testing is required. MassDEP regional offices inspect these systems on a regular basis and ensure that systems comply with the testing and notification requirements.

Is MassDEP the agency responsible for ensuring that local water systems meet the standards set by the federal government?

Yes, MassDEP has primacy to conduct the drinking water program in Massachusetts. MassDEP also ensures that the PWSs comply with the standards and takes enforcement action when necessary.

Do people who have private wells need to have their water tested?

Local Boards of Health (BOH) regulate private wells, not MassDEP. At a minimum, well owners should have private wells tested annually for bacteria and nitrates. In addition, MassDEP has a recommended list of contaminants and testing frequencies for private wells. Contact MassDEP at 617-292-5770 for this listing. However, BOHs may have existing regulations that require homeowners to test for additional substances. If a community wishes to pass a BOH regulation, they should consult MassDEP's guidance, Private Well Guidelines (see below).

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