Free Wisconsin water report: PFAS & lead levels for every water system, worst-affected cities, and EPA violations. Check your ZIP.
Wisconsin's 5.9 million residents draw drinking water from an unusually water-rich landscape – the state borders two Great Lakes, contains over 15,000 inland lakes, and sits atop productive groundwater aquifers. Milwaukee and other lakefront communities draw from Lake Michigan, one of the largest freshwater bodies on Earth. Inland cities like Madison rely on groundwater from the state's sandstone and glacial aquifers. Rural communities – and Wisconsin has many – depend heavily on private wells. The Wisconsin Department of Natural Resources (DNR) oversees water quality regulation, and the state has a long history of relatively aggressive environmental protection.
Wisconsin's most prominent PFAS contamination case is not military in origin – it is industrial. Tyco Fire Products (now Johnson Controls) in Marinette, on the Michigan border, manufactured AFFF firefighting foam at its facility and tested it at a nearby fire training area in the Peshtigo area. The resulting PFAS contamination has affected groundwater, surface water, and private wells across a wide area of northeastern Wisconsin.
The Marinette/Peshtigo contamination is one of the most significant non-military PFAS cases in the country. PFAS compounds – including PFOA, PFOS, and several other variants – have been detected in hundreds of private wells in the area. Tyco/Johnson Controls has provided bottled water, installed treatment systems, and connected some affected residents to municipal water, but the extent of the contamination continues to be defined as testing expands. The plume has reached the Menominee River, which flows into Green Bay, and PFAS has been detected in fish and surface water downstream.
Beyond Marinette, Wisconsin's PFAS sources include military installations (General Mitchell Airport/128th Air Refueling Wing in Milwaukee, Truax Field/115th Fighter Wing in Madison), municipal airports, and industrial facilities across the state. The state's dairy industry raises additional concerns – biosolids applied to agricultural land as fertilizer can contain PFAS, and Wisconsin's agricultural density means this pathway potentially affects a large area.
Wisconsin has adopted some of the most specific PFAS groundwater standards in the country. The DNR established recommended groundwater enforcement standards of 20 ppt for PFOA and 20 ppt for PFOS, along with standards for several other PFAS compounds. The state has also invested in PFAS monitoring and has been proactive about requiring testing at potential contamination sites.
The Marinette/Peshtigo case is nationally significant because it demonstrates that PFAS contamination is not exclusively a military problem. Tyco's fire training operations were civilian in nature, and the contamination pattern – spreading outward from a concentrated source through groundwater – mirrors what has happened at military bases. The case has influenced how other states approach industrial PFAS sources.
Among Great Lakes states, Wisconsin's approach is more aggressive than Ohio or Indiana but less comprehensive than Michigan, which has invested the most of any state in PFAS testing and remediation. Minnesota has dealt with its own major PFAS case (the 3M contamination in the east metro) and has adopted similarly strict standards.
Wisconsin's high rate of private well usage – the state has an estimated 800,000 private wells – creates a monitoring gap. Public water systems are tested regularly, but private wells are the homeowner's responsibility, and many have never been tested for PFAS.
Wisconsin's combination of Great Lakes surface water, productive aquifers, and extensive private well usage means water quality varies significantly across the state.
1. Check your water quality using our free tool. Municipal system data is comprehensive; private well data depends on voluntary testing and proximity to known contamination sources. 2. If you live in the Marinette/Peshtigo area or near any identified PFAS source, get your well tested. The Wisconsin DNR maintains a list of known contamination sites. Our water filter guide covers treatment options certified for PFAS reduction – reverse osmosis and certain granular activated carbon systems are the most effective. 3. Dairy farm communities should ask about biosolids application history in their area. PFAS from biosolids can leach into groundwater and affect private wells downhill from application sites. A detailed water report can provide context for your specific location. 4. Milwaukee and other Lake Michigan communities face different concerns – primarily lead from aging service lines and disinfection byproducts from treating lake water. Check your data to see which contaminants are relevant for your supply.
Wisconsin's water quality legacy reflects the state's dual identity: agricultural heartland and industrial powerhouse. The Fox River, which flows through the heart of the state's paper industry before entering Green Bay, was one of the most polluted rivers in the country by the mid-20th century – contaminated with PCBs from paper mills and other industrial operations. The Fox River Superfund cleanup, one of the largest in the nation, has been ongoing since the 1990s.
The Marinette PFAS contamination emerged in the 2010s as testing technology improved and awareness of PFAS grew nationally. Tyco Fire Products had manufactured AFFF at the Marinette facility for decades, and field testing of the foam at a nearby site had introduced PFAS directly into the soil and groundwater. As testing expanded outward from the source area, contamination was found in an ever-widening circle of private wells – a pattern that continues as the full extent of the plume is mapped.
The Wisconsin DNR's response has included establishing PFAS standards, requiring responsible parties to provide alternative water supplies, and expanding testing programs. The state's approach has been more structured than many states, though advocacy groups and affected residents have pushed for faster action and stricter standards.
Wisconsin's dairy industry is central to its identity and economy, and the intersection of PFAS with agriculture has raised difficult questions. Biosolids – treated sewage sludge – have been applied to Wisconsin farmland for decades as a cost-effective fertilizer. When PFAS was found in biosolids, the implications extended to soil, groundwater, crops, and potentially milk and meat. The state has been studying PFAS uptake in agricultural systems, but the science is still developing.
Milwaukee's water story includes its own legacy challenge: lead service lines. The city has tens of thousands of lead service lines connecting older homes to the water main, and replacement is proceeding gradually with federal infrastructure funding. Lake Michigan water is treated to control corrosivity and minimize lead leaching, but the fundamental issue – lead pipes connecting treatment plant water to household taps – remains until replacement is complete.
The Great Lakes themselves face PFAS contamination from multiple sources across multiple states and Canada. PFAS has been detected in Great Lakes fish, water, and sediment, raising questions about exposure through food sources beyond drinking water. Wisconsin's fishing culture – both recreational and subsistence – makes this an exposure pathway that matters to many residents.
Check your address to see the latest data for your part of Wisconsin. Whether you are on Lake Michigan water, a municipal well, or a private well in dairy country, your specific water source determines your risk profile.