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Acton’s Water Quality Testing Program


Yes. The Acton Water District regularly tests for all contaminants required under the Safe Drinking Water Act. The test frequency varies, depending on the contaminant. Contaminants which are more likely to be found in drinking water and that may have acute health effects are tested the most frequently. For example, the Acton Water District collects 29 samples for coliform bacteria each month, while more unusual contaminants, such as pesticides, are tested once every three years. If the level of a contaminant is above the health standard, then the District must notify the public and corrective action must be taken immediately.

What are the current drinking water standards?

Under the Safe Drinking Water Act passed in 1974, the U.S. Environmental Protection Agency (EPA) established drinking water standards regulating over 100 different contaminants. These standards are divided into two categories: primary standards and secondary standards. Primary standards limit the levels of contaminants that may endanger public health, and they are legally enforceable. Secondary standards are non-enforceable guidelines for contaminants that affect the aesthetic appearance of drinking water. These contaminants have no known adverse health effects at the concentrations typically found in drinking water, and are tested for because they may affect the taste or smell of drinking water.

The Town of Acton has ground water VOC cleanup standards that are more stringent than the EPA’s. The concentration of any single VOC can not be greater than one part per billion, or if a combination of VOCs are present, five parts per billion.

How are the standards set?

The EPA has determined a maximum contaminant level (MCL) for all regulated contaminants. MCLs are enforceable standards, based primarily on protecting public health in the most stringent manner possible. Prior to setting MCLs, the EPA sets maximum contaminant level goals (MCLGs), which equal the concentration of a contaminant that may be safely consumed over a lifetime with no adverse health effects. For all carcinogens (substances which cause cancer), the MCLG is set at zero. The MCL is then derived by taking the number closest to the MCLG that is technically and economically feasible. Ultimately, the MCL should equal the MCLG for each contaminant. For many contaminants, such as fluoride, this is already true.

What types of contaminants are included under the primary standards?

The contaminants under the primary standards are divided into four groups:

  • Inorganic chemicals
  • Organic chemicals
  • Radionuclides
  • Microorganisms

Information on some of these contaminants can be obtained by clicking on the links at the top of this page.

What are the health effects of these contaminants? Where do they come from?

  • Inorganic chemicals mainly consist of toxic metals, such as lead, copper or mercury, as well as many others. The effects of these substances are varied. Some inorganic chemicals such as fluoride and arsenic naturally occur in water in certain areas, while lead and copper might come primarily from pipes or human activity.

  • Organic chemicals (substances containing carbon) include trihalomethanes, pesticides and volatile organic chemicals (VOCs). These contaminants may cause liver, kidney and spleen damage, anemia, central nervous system problems and cancer. VOCs may also cause reproductive disorders and birth defects. The source of these chemicals varies. Trihalomethanes are formed if the chlorine added to drinking water reacts with natural organic matter in the water. Pesticides may come from runoff or leaching from insecticide or herbicide use. VOCs, which include paint thinners, varnishes and fuel additives, may come from discharge from factories or leaching from landfills.

  • Some common radionuclides are radon, radium and uranium, which all may increase the risk of cancer. Naturally occurring radionuclides, as well as man-made radionuclides, may be absorbed into water from the soil and bedrock.

  • Microorganisms include bacteria, viruses and parasites. The most common effects of these microorganisms are cramps and diarrhea. These contaminants come from human and animal fecal waste.

  • Nitrate, an inorganic chemical, can have serious health effects in young infants. High levels of nitrate can cause "blue baby syndrome" (methemoglobinemia), which can be life threatening without immediate medical treatment. Nitrate is a major component in fertilizer, and comes primarily from runoff from the land surface.

What Are Some of the Contaminants included under the Secondary Standards? Why Don't They Have MCLS?

These include chemicals such as chloride, iron, sulfate and many others. These chemicals may cause drinking water to have an unpleasant taste or odor, or to have an unattractive appearance, but they pose no known health risks at the concentrations normally found in drinking water.

What is being done to ensure that my drinking water is free of these contaminants?

All of the Acton Water District’s sources are treated in order to minimize the concentration of impurities. For example, nine of Acton’s well sites are aerated to prevent any VOCs from entering the drinking water. Although many of these wells do not have a history of VOC contamination, this was seen as a proactive way to provide maximum public health protection. In addition, a small amount of fluoride is added to promote dental health, and the pH of the water from all wells is adjusted to minimize leaching of pipe materials, such as lead and copper, into drinking water.

On going, regular testing of the District’s water helps detect any water quality problems early on. Modern technology makes it easier to reliably detect contaminants at very low concentrations. The Acton Water District uses certified drinking water laboratories that follow state-of-the-art analytical techniques. A detection of any contaminant would result in follow up, including re-testing and treatment, or other actions to eliminate any health concern. This will ensure that Acton’s water is of the highest quality possible.