Drinking Water Concerns

Some drinking water supplies contain chemicals that can affect our health.Woman holding a glass of water

While most public water systems and private wells in Wisconsin provide safe drinking water, some may contain chemicals that can affect our health. Below is information on the chemicals most commonly found in Wisconsin's drinking water.

 

Arsenic

Arsenic is primarily an issue in private wells. The only way to know if your private well has arsenic is to test. You should test your well for arsenic once every five years and take action if the arsenic level is above 10 micrograms per liter (µg/L) (P-45012- English, Spanish, Hmong). You can learn about arsenic exposure, health effects, and standards on our Arsenic page.

Bacteria

Bacteria can be an issue in public water systems or private wells. Public water systems regularly test for bacteria. If warranted, the system will issue a Boil Water Notice (P-44589). It is important to follow the steps described in the notice to protect yourself and your family from illness.

The only way to know if your private well has bacteria is to test. You should test your well for bacteria at least once a year and take action if bacteria are present (P-02132 - English, Spanish, Hmong). You can learn more about health effects of bacteria and what to do if your well has bacteria on our Bacteria in Private Wells page.

Flooding

Flooding can affect drinking water quality. If your public water system has been affected by a flood, they may issue a Boil Water Notice (P-44589). It is important to follow the steps described in the notice to protect yourself and your family from illness. You can learn more about what to do if your house has been affected by flooding on our Flooding: Drinking Water Issues page.

Private wells can also be affected by flooding. If your well casing becomes inundated or if you have a shallow well and nearby areas are flooded, you should take action to protect yourself and your family (P-02362). You can learn more about the actions to take if your well has been affected by flooding on our Flooding: Drinking Water Issues page.

Fluoride

Fluoride is a naturally occurring mineral that keeps teeth strong and reduces cavities at the right levels. In many parts of the state, fluoride levels in drinking water are naturally low and communities add fluoride to protect the oral health of its residents. 

Because levels of fluoride in drinking water varies across the state, private well owners should test for fluoride at least once every three years and take action if levels are too low or too high. 

  • Fluoride levels less than 0.7 mg/L are too low for oral health protection. At these levels, there is not enough fluoride present to prevent cavities or support strong teeth. Parents should talk with their child's medical or dental professional about supplementing with additional fluoride sources to ensure adequate oral protection.
  • Fluoride levels between 0.7 and 2 mg/L support good oral health. No additional actions are needed at these levels. 
  • Fluoride levels between 2 and 4 mg/L are too high for young children. Children that are 8 years old and younger should use an alternative source of drinking water to prevent changes in the appearance of the teeth's enamel. Alternative sources of drinking water can included bottled water, water treated with a device certified to remove fluoride, and water from a private well or public water system that has fluoride levels between 0.7 and 2.0 mg/L. 
  • Fluoride levels greater than 4 mg/L are too high for everyone. Long term exposure to high levels of fluoride can cause bones to be brittle and fragile. Everyone should use an alternative source of drinking water to reduce the potential for health impacts. Alternative sources of drinking water can included bottled water, water treated with a device certified to remove fluoride, and water from a private well or public water system that has fluoride levels between 0.7 and 2.0 mg/L. 

Lead

Pipes, faucets, and other plumbing components in a home can contain lead. You should check your home for these sources and take action to protect yourself and your family from lead (P-02602) if identified. You can also learn more about these sources and the actions to take on our lead in water page.

Lead can be in other places in your home. Learn more about where lead is found on our Sources of Lead Exposure page.

Manganese

Manganese can be an issue in public water systems or private wells. Public water systems in Wisconsin test for manganese every nine years. Manganese can turn the water a brown, rust color, cause staining of faucets, sinks, or laundry, and make the water have an off-taste or odor. Contact your water utility if you notice these issues in your home. If manganese levels are too high, the system may issue a public notice. It is important to follow the steps described in the notice to protect yourself and your family.

Manganese can turn the water a brown, rust color, cause staining of faucets, sinks, or laundry, and make the water have an off-taste or odor. If you notice these issues, you should test your water for manganese. You should take action to protect yourself and your family if manganese levels are greater than 300 micrograms per liter (µg/L). You can learn more about health effects and steps to take if levels are high on our Manganese in Drinking Water page.

Manure

Manure can contaminate private wells if it runs off from fields or overflows storage tanks during heavy rain fall events or is spilled. Manure contains germs that can make people sick. Common symptoms include diarrhea, nausea, vomiting, cramps and fever. The elderly, young children, and people with a weak immune system are at the most risk for getting sick.

If you suspect that your water is contaminated with manure, you should take action right away to protect yourself and your family (P-02952). You can learn more about health effects, risk factors, and actions to take if your well has been contaminated with manure on our Manure in Private Wells page.

Nitrate

Nitrate is primarily an issue in private wells. The only way to know if your private well has nitrate is to test. You should test your well for nitrate at least once a year and take action if nitrate levels are above 10 milligrams per liter (mg/L). You can learn more about the health effects of nitrate on our Nitrate in Private Wells page.

PFAS

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a class of manmade chemicals. Some PFAS have been found in certain public water systems and private wells in Wisconsin. We are still learning about where these chemicals are found and their health effects. You can learn more about PFAS exposure, health effects, and standards on our PFAS page.​

Other chemical concerns?

The chemical list has information on chemicals in water, along with how we come in contact to chemicals in the air or soil.

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Last Revised: September 1, 2022