Madison tap water meets all federal and state standards for drinking water safety.
Per and Polyfluoroalkyl Substances (PFAS)
PFAS, or Per and Polyfluoroalkyl Substances, is a class of thousands of chemicals used in everything from food packaging and cookware to upholstery, clothing and firefighting foam. The chemicals do not break down in the environment and are commonly found in dust, air, soil and water.
Madison Water Utility first began in-depth testing for a broad spectrum of PFAS chemicals at all city wells in 2019 at the urging of community members who petitioned the Water Utility Board for comprehensive monitoring. Testing for PFAS isn’t required by state or federal regulators, and most communities in Wisconsin do not test drinking water for the compounds.
- Samples were collected in May from each active well (18) and subjected to analysis by US EPA Method 537.1 at the WI State Lab of Hygiene
- Test results are from the WI DNR Voluntary Drinking Water PFAS Sampling Project for Municipal Systems – funded by a US EPA grant.
- Reporting limits (RL) vary by PFAS but generally are below 1 part per trillion (ppt) for some PFAS and below 2 ppt for others.
Summary of Test Results
None of the 18 PFAS tested were found at ten of the eighteen wells tested
PFOS (RL: <1 ppt) was detected at a single well (#16) and PFOA (RL: <2 ppt) was not detected at any of the 18 wells tested
PFHxS (RL: <1 ppt) was most commonly detected; it was found at eight wells at levels ranging from 0.96 to 5.51 ppt
PFBS (RL: <1 ppt) was found at three wells (#6, #9, and #14) ranging from 1.02 to 1.77 ppt while PFHxA (RL <2 ppt) was found at one well (#14) and measured 2.08 ppt
Past Testing Results
Wisconsin Department of Health Services uses a "Hazard Index" to evaluate the risk from exposure to mixtures of PFAS. This approach is commonly used by environmental health professionals to assess health risk related to groundwater contaminants. View the 2021 Hazard Index figure here.
To receive lab reports generated during 2021 or 2020 PFAS testing (about 300 pages), email email@example.com
Yes, Madison tap water meets all federal and state standards for drinking water safety. If you have special circumstances or want to further purify your water, home filtration (activated carbon filters and reverse osmosis) is an option to reduce PFAS levels.
There are 21 well facilities across Madison that provide the city's water and protect from fires. Wells 15 and 23 are not in service.
Which wells serve your home? Enter your address here to find out
New analytical technology can detect PFAS chemicals down to a fraction of one part-per trillion. But looking for chemicals at such ultra-trace levels means that many detections reported by labs are too low to accurately measure. Levels that are below two parts per-trillion are often reported as estimates. Some results may also be false positives.
Madison Water Utility will test all operating wells again in 2021.
Thousands of types of PFAS chemicals have been manufactured, but a just handful have been well-studied or tied to known health risks. Most drinking water regulation focuses on two types of PFAS compounds called PFOA and PFOS, which have been phased out of use in the United States. Madison Water Utility detected PFOA and/or PFOS in sixteen wells. The estimated level of PFOA + PFOS found ranged from 0.5 to 3.4 parts per trillion. The DNR is considering imposing a safe drinking water limit of 20 parts per trillion for PFOA and PFOS in Wisconsin.
Madison Water Utility also found a broad range of other types of PFAS chemicals during its testing. Most types are not regulated by any state. Others are regulated at much higher levels than PFOA and PFOS.
For example, over 80% of the PFAS detected in Well 9 is a single chemical called PFBA. The most restrictive health-based guideline for PFBA in the United States comes from the Minnesota Department of Health and is set at 7,000 parts-per-trillion. Madison Water Utility found a total PFAS concentration in Well 9 of 47 ppt, with 37 ppt coming from PFBA.
While the very low levels of PFAS found in Madison wells don’t require large-scale wellhead treatment, Madison Water Utility often gets questions about at-home filters. It is possible to reduce PFAS chemicals in water using a home filter. A recent study by Duke University and North Carolina State University analyzed the effectiveness of a variety of household filters at removing PFAS from tap water.
About one percent of the water pumped to Madison homes is used for drinking and cooking. The rest is used for flushing toilets, doing laundry, dishes, outdoor watering and other needs.
Madison Water Utility first discovered PFAS in two Madison wells in 2017 while conducting limited testing at wells near landfills and the airport. One of those wells – Well 15 located on East Washington Ave. – was shut down in 2019 amid community concerns about PFAS chemicals found there. Madison Water Utility just completed a $50,000 feasibility study looking at possible PFAS treatment at Well 15. The utility will now evaluate whether installing a treatment system at Well 15 is the best, most cost-effective option for meeting water supply needs on Madison's east side. The utility believes the chemicals detected in that well likely migrated from Truax Air Field, about a mile away. It’s unclear where PFAS chemicals found in other city wells are coming from.
High concentrations of certain types of PFAS chemicals have been shown to affect health.
View more information on Public Health Madison and Dane County website.
Test results from 2019
View 2019 PFAS testing results here.