common contaminants

What's in our water?

Wisconsin is rich in water resources, yet too many families lack access to safe drinking water. Our public water supply systems and private wells are vulnerable to a host of threats, including agricultural runoff, lead from aging infrastructure and toxic contaminants such as PFAS. Understanding the source of these contaminants is the first step in holding industry and government accountable to our environmental laws.

Girl Drinking Water


Nitrates in Wisconsin’ s groundwater come from 3 main sources–agricultural fertilizers, manure, and residential septic systems. It is estimated that 10% of wells across the state have unsafe levels of nitrates. In areas where agriculture is the dominant land use, the percentage of contaminated wells can be much higher. A recent study in rural southwest Wisconsin revealed that 42% of private wells tested positive for unsafe levels of nitrates or bacteria.


At least 176,000 Wisconsin homes and businesses receive water from aging lead service lines, including many daycare facilities and schools. Thousands of children in Wisconsin have elevated levels of lead in their bodies. Lead exposure can result in irreversible damage to the brain, kidneys and nervous system. Lead poisoning is a statewide problem that affects families in the cities of Menasha, Milwaukee, Racine, and Watertown and the counties of Buffalo, Green Lake, Pepin, Richland, Rock, and Sheboygan.


PFAS (pronounced “p-fass”) are synthetic chemicals found in firefighting foams and household goods such as non-stick cookware. PFAS move quickly through groundwater and have been linked to a range of serious health concerns. Communities with known PFAS contamination include Marinette, Manitowoc, Milwaukee, Madison, Baraboo, Sparta and Camp Douglas. The true extent of the problem is unknown, as most public water systems have yet to be tested for PFAS.