Common Drinking Water Contaminants and Issues in Vermont

Vermont’s bedrock contains naturally occurring elements such as radioactive elements (uranium, radium and radon), iron, arsenic, and manganese. Nitrate is a compound that occurs naturally in water in low background amounts, while fluoride is a naturally occurring mineral.

Some contaminants are human-made and enter water sources because of human activities.

Natural Drinking Water Contaminants and/or Issues

The Health Department recommends testing your private water source for natural drinking water contaminants including coliform bacteria and hardness.


Coliform is a family of bacteria common in soils, plants and animals. The coliform family is made up of several groups. One group is fecal coliform, which is found in the intestinal tracts of warm-blooded animals including humans. Fecal coliform in drinking water or at swimming sites means that human or animal waste has been or is present. This may be a cause for concern because many diseases can be spread from human or animal waste.

  • The presence of some fecal material in lakes, ponds, and rivers is part of the natural environment. As long as the level of fecal coliform bacteria is low, swimming is relatively safe.
  • In drinking water, however, any fecal coliform presence is a warning sign that action should be taken.

Do not drink water that has tested positive for bacterial contamination.

Health Effects of Coliform in Drinking Water

Coliform or other bacteria in drinking or swimming water will not necessarily make you ill. However, since these organisms are present, other disease-causing organisms may also be present. Health symptoms related to drinking or swallowing water contaminated with bacteria generally range from no effects to cramps and diarrhea (gastrointestinal distress).

Two common waterborne diseases are giardiasis and cryptosporidiosis; both cause intestinal illness. E. coli 0157:H7 has also been associated with drinking contaminated water and can cause intestinal illness. In very rare cases, it can cause hemolytic uremic syndrome, a serious kidney condition.

The Health Department Laboratory performs tests for total coliform and E.coli bacteria. These tests do not detect organisms such as giardia or cryptosporidium, or specify which strains of E.coli are present, which is why it is important to follow all of the necessary treatment and disinfection recommendations.


Hardness is not a specific component of water. It comes from the amount of calcium and magnesium ions in water. Hardness is expressed in terms of calcium carbonate (CaCO3). Water with less than 75 milligrams per liter (mg/L) is considered soft, 76 – 150 mg/L moderately hard, and above 150 mg/L, hard.

Health Effects of Hard Drinking Water

There are no known health risks associated with consuming hard water. In fact, studies have shown that people who regularly consume hard water throughout their lifetime have a lower rate of cardiovascular disease.

Household Problems Associated with Hard Water

  • Gray staining of washed clothes
  • Scum on wash and bath water following use of soap or detergent
  • Soaps not lathering as much
  • Buildup of scale on electric heating elements and boilers
  • Reduced water flow in hot water distribution pipes due to scale buildup
  • Accumulation of whitish-gray scale in tea kettles and other containers used to boil water

Human-made Drinking Water Contaminants and/or Issues

Human-made chemicals get into drinking water as a result of human activities. Examples include:

  • Herbicide sprayed too close to a well or other water supply
  • Accidental chemical spill
  • Improper disposal of chemicals down storm drains, household drains, or down the toilet
  • From old manufacturing sites where chemicals were disposed of improperly.

As with naturally occurring chemicals, most health effects result when people drink water contaminated with human-made chemicals over a long period of time. The Vermont Tracking portal includes data about four human-made chemicals: atrazine, di(2-ethylhexyl) phthalate (DEHP), tetrachloroethylene (PCE) and trichloroethylene (TCE). Other human-made contaminants include volatile organic compounds (VOCs) and Perfluorooctanoic Acid (PFOA).


Atrazine is an herbicide that is widely used as a weed killer. Although its uses were greatly restricted in 1993, it can still be in the environment. People who drink water that contains high levels of atrazine over many years may be at greater risk for cardiovascular problems and reproductive difficulties.                                                   

The maximum contaminant level (MCL) for atrazine is 3 micrograms per liter (µg/L), which is equal to 3 parts per billion (ppb).

Di(2-ethylhexyl) phthalate (DEHP)

Di(2-ethylhexyl) phthalate (DEHP) is the most commonly used of a group of related chemicals called phthalates or phthalic acid esters. The greatest use of DEHP is as a plasticizer (softener) for polyvinylchloride (PVC) and other polymers including rubber, cellulose, and styrene. Several packaging materials and tubings used in the production of foods and beverages are PVC-contaminated with phthalic acid esters, primarily DEHP. Some people who drink water containing DEHP more than the maximum contaminant level (MCL) over many years may be at greater risk for liver problems, reproductive difficulties, and cancer.

The current MCL for DEHP in drinking water is 6 micrograms per liter (µg/L), which is equal to 6 parts per billion (ppb).

Tetrachloroethylene (PCE)

Tetrachloroethylene (PCE) is a solvent used in the textile industry and as a component of aerosol dry-cleaning products. It can enter water systems through discharges from factories and dry-cleaning facilities. Consuming drinking water with high levels of PCE over many years may increase the risk for liver problems and cancer.

The current maximum contaminant level (MCL) for PCE is 5 micrograms per liter (µg/L), which is equal to 5 parts per billion (ppb). Vermont has an action level of 1 µg/L for PCE in drinking water.

Trichloroethylene (TCE)

Trichloroethylene (TCE) is a solvent that is primarily used to remove grease from fabricated metal parts and is also used in the production of some textiles. Consuming drinking water that contains high levels of TCE for many years may lead to increased risk for liver problems and cancer.

The current maximum contaminant level (MCL) for TCE is 5 micrograms per liter (µg/L), which is equal to 5 parts per billion (ppb). Vermont has an action level of 0.5 µg/L for TCE in drinking water.