Frequently Asked Questions

PFAS are a class of chemicals widely used in cookware, food packaging, stain and water-resistant clothing, upholstery and firefighting foams. The compounds do not degrade and are showing up in dust, soil and water worldwide.

High levels of PFAS exposure have been linked to a variety of health concerns, including increased risk of some types of cancer. So far, PFAS are not regulated under the Safe Drinking Water Act.

View the Public Health Madison Dane County information page on PFAS

Levels of PFAS detected in Madison wells are below both US EPA’s federal standards(link is external) for six PFAS in drinking water and the Wisconsin Department of Health Services recommended groundwater standards(link is external), both of which are set to protect public health..

According to Public Health Madison Dane County, the levels we're seeing in Madison are not considered a threat to health.

View the Public Health Madison Dane County information page on PFAS

You can enter your address here to see which of Madison's 23 wells serve your home. Many addresses are served by more than one well. The information is meant to be an estimation of the service areas of the wells, averaging a range of operational conditions over the course of a year. Service areas for any well can change based on season, weather conditions (i.e. drought, heavy rainfall), loss of service at nearby wells, or other unforeseen changes in system operation.

Madison Water Utility believes the low levels of PFAS chemicals detected at Well 15 on East Washington Ave. (currently shut down) have likely traveled in groundwater over several decades from Truax Air Field, where firefighting foams have been used. PFAS chemicals have been found in high concentrations in groundwater at the base.

Unfortunately, cleaning up known contamination at Truax Air Field will not decrease PFAS detections at Well 15 for years or perhaps decades. It takes 35 to 50 years for PFAS to travel in groundwater from the air base to the well. We believe the chemicals we're seeing in the well now were used at the air base several decades ago.

The sources of PFAS at other city wells are currently unknown.

• Madison Water Utility has rigorously tested all active wells for up to 30 PFAS at least annually since 2019. That testing consistently finds at least one PFAS at four wells – Well 6, Well 9, Well 11, and Well 14.
• Some PFAS are occasionally found at five other Madison wells – Well 7, Well 13, Well 16, Well 26, and Well 27.
• Except for PFBA and PFHxS at some wells [6,9,11, and 14] individual PFAS levels at a particular well typically measure 2 parts per trillion (ppt) or lower – a level below which not every lab can reliably measure. Year-to-year variations in test results can stem from changing detection limits at a testing lab or the analytical method used.

Find more information on PFAS detections.

Public Health Madison Dane County does not recommend that people invest in filters or bottled water. Madison's water meets all state and federal standards for drinking water quality. 

However, in almost all cases, reverse osmosis and dual-stage (activated carbon-based) filters were able to reduce all analyzed compounds to below detection. 

The Wisconsin Department of Health Services (DHS) recommends using granular activated carbon (GAC) or reverse osmosis (RO) filters to reduce PFAS in home drinking water. 

The most common household filters include:

• Faucet- mounted filters seemed to be the most effective. These filter types were able to significantly reduce PFAS of interest to Madison residents, including PFOS, PFOA, PFBA, and PFHxS, and next generation PFAS like GenX. In every case but one, they reduced each compound tested to below 1 ppt.
• Refrigerator filter results were inconsistent due to variations in size from house to house. Larger fridge filters with more activated carbon were more effective.
• Pitcher filters were reliable at reducing PFAS but not consistently to below 1ppt.
• Single-stage under- the- sink filters were very effective at removing PFOS and PFHxS – however less effective at removing PFOA and GenX, and not effective at removing PFBA.

Visit the DHS Website for more information about PFAS and home-filtration. 

Madison Water Utility has taken action to remove PFAS from our water. The water utility has been investigating PFAS contamination in our drinking water since 2017 when it was first discovered at Well 15 on Madison's eastside. Well 15 was subsequently shut down amid community concern and has not operated since. 

Madison has comprehensively tested all wells for PFAS over the last five years and Well 15 is the only City of Madison drinking water well that does not currently meet EPA PFAS standards. 

A treatment system to remove PFAS from Well 15’s water is currently under construction. The expectation is for the PFAS treatment system to be operational by Summer 2025. This treatment is expected to remove PFAS to a non-detectable level. 

Check out the Well 15 Project Webpage for more information about the PFAS Treatment System at Well 15.