Water Quality Issues

Rusty outdoor water faucet

Water is a precious natural resource. Over 17% of Wisconsin is covered in water. We also benefit from the groundwater that flows beneath us.

We come into contact with water when we eat or drink from it, play in it, or use it for our homes, businesses, and farms. Knowing about water quality issues is important to our good health.



General Drinking Water Information

Public Water Systems 

Water Quality Data is a Department of Natural Resources (DNR) webpage with data about Wisconsin’s drinking water and groundwater quality.

Consumer Confidence Reports provide an annual report on public water systems. This includes test results and violations. 

Private Well Water

The DNR provides recommendations on private drinking water well testing and an updated list of labs that test private well water for Bacteria (PDF, 31 KB) and Contaminants.

The DNR page, "What's Wrong with My Water?" helps private well owners:

  • Choose the right lab tests to give a definitive diagnosis;
  • Decide whether a water problem is more likely to be a health concern or a nuisance problem;
  • Find a laboratory certified to do testing;
  • Choose a possible fix; and
  • Identify licensed professionals who can help.

Approved Treatment Devices for Contaminants - Wisconsin Department of Safety and Professional Services

Surface Water

Direct and indirect pollution sources of Wisconsin surface waters - Wisconsin DNR

Environmental Contaminants in Drinking Water

A - L


Arsenic is a natural element found in soil and bedrock throughout Wisconsin. Under certain conditions, arsenic can be released into groundwater and enter water wells.


Aluminum is a naturally occurring metal that is found in the earth’s crust. Aluminum salts are used as coagulants to purify municipal water that is drawn from lakes or reservoirs. Aluminum-contaminated water has no taste or odor. However, very high aluminum levels can sometimes cause water to have a bluish color.

Aromatic Concentrates

Aromatic concentrates are purified mixtures of chemicals found in crude oil. These mixtures are used to make gasoline and other fuels. They are strong-smelling liquids that range in color from yellow to black. If spilled, aromatic concentrates evaporate quickly. However, part of the spill can go into the air, the soil, and sink down into the groundwater.


Atrazine is a white crystal solid. Farmers have used it widely as a weed killer on corn fields since the early 1960s. A recent survey of rural Wisconsin wells found widespread atrazine contamination. In most cases, the amounts detected did not pose a serious risk to health. However, the Wisconsin Department of Agriculture, Trade, and Consumer Protection has taken action to reduce atrazine use to prevent any more groundwater contamination.


A common contaminant in wells.


Benzene is a widely used industrial chemical. It quickly evaporates from water or soil. If benzene leaks from buried storage tanks or landfills, it can contaminate nearby drinking water wells. Benzene can move long distances in groundwater.


Cadmium is a metal found naturally in the earth's crust. The normal intake of cadmium (1-3 micrograms/day) does not appear to cause health problems. People can be exposed to increased amounts of cadmium by drinking contaminated water, which is typically caused by improper disposal of industrial chemicals.

Carbon Tetrachloride

Carbon tetrachloride (Carbon tet) is a non-flammable, colorless liquid with a heavy, sweet odor. Carbon tet may contaminate groundwater near locations where the chemical was improperly disposed of. Since the compound is heavy, some of the spilled liquid will sink through soil and enter groundwater.


Chlorine is a poisonous, greenish-yellow gas described as having a choking odor. It is a very corrosive, hazardous chemical. Usually combined with other chemicals, it is used to disinfect water, purify metals, bleach wood pulp, and make other chemicals. Low-level exposure can occur when water containing chlorine is used for drinking or for food preparation.


Cyanide is sometimes found in contaminated drinking water. People can be exposed when they drink contaminated water. Cyanide is very poisonous. Cyanide can exist as a gas, liquid, or white crystal powder. Cyanide is used in the electroplating industry, in metal cleaning operations, and as an industrial bug killer.

1, 2 - DCA

1,2-DCA is a thick, colorless liquid which has a pleasant odor and sweet taste. In the home, 1,2-DCA can be found in some cleaning solvents, pesticides, glues, varnishes, and strippers. When 1,2-DCA enters the environment, it can seep into the soil or evaporate into the air. It eventually may reach groundwater and contaminate local drinking water supplies.


Lead was used in many home plumbing systems and could be a toxic contaminant in the home.

Lead Arsenate Pesticides

Lead Arsenate Pesticides were used commonly to control agricultural pests in Wisconsin. The pesticide residues bind tightly to the soil, and some has remained there for decades, and may pose a health risk to humans when the land changes from agriculture uses.


M - Z


Common element in minerals, rocks, and soil that is naturally found in groundwater but can be harmful at high levels.

Manure Contamination

Manure-related problems are usually caused when liquid manure is spread on fields during the late winter and early spring months. During these times, manure cannot be tilled in or adequately absorbed by the soil.


Molybdenum is a metal that occurs naturally in the earth’s crust and is usually found in very small amounts. It is an important dietary nutrient in very small quantities, yet too much molybdenum may cause health problems. In nature, it can be found in poorly drained, highly organic soils and as part of some minerals found in soil and rock. Molybdenum is occasionally found naturally in groundwater.


A common contaminant in drinking water. It is largely used in agricultural and residential fertilizers.

Old Dumps and Landfills

Many old dumpsites had no liners to prevent groundwater contamination. When the dumps were full, they were typically covered with loose topsoil. Rainwater and precipitation can seep into the waste and carry chemicals to the groundwater below. Because some old dumps used wetlands for disposal sites, the wastes were directly in contact with the groundwater table.


Pesticides used on corn, soybeans, and other crops can affect water supplies.

Polychlorinated Biphenyls (PCBs)

PCBs are a group of 209 different compounds. PCBs are human-made and have no smell. They are yellow, oily liquids that don’t easily burn. There are no natural sources of PCBs. For most people, eating fish or other seafood caught from polluted water is the main way  they are exposed to PCBs.

Polycyclic Aromatic Hydrcarbons (PAHs)

Most PAHs in the environment are from incomplete burning of carbon-containing materials like oil, wood, garbage, or coal. Charcoal-broiled foods, especially meats, are a source of some PAH exposure. Shellfish living in contaminated water may be another major source of exposure. PAHs may be in groundwater near disposal sites where construction wastes or ash are buried; people may be exposed by drinking this water.


A naturally occurring element that is found in some of Wisconsin's groundwater in low amounts.


A naturally occurring element that is found in some of Wisconsin's groundwater in low amounts.


A naturally occurring element commonly found at low levels in drinking water supplies.


A mineral that occurs naturally in the environment. Non-radioactive or "stable strontium" is very common in soil and bedrock and may dissolve, entering groundwater.


Sulfates are mineral salts containing sulfur. Sulfate salts are found in some Wisconsin soils. Mines, tanneries, steel mills, pulp mills, and textile plants also release sulfates into the environment. Industrial wastewater, household wastewater, runoff from a hazardous waste site, or naturally decaying material can put sulfates into waterways, rivers, lakes, and streams. Wastes that contain sulfates seep through soil and contaminate groundwater.


Trichloroethylene (TCE) is a human-made chemical that does not occur naturally in the environment. TCE can enter groundwater and surface water from industrial discharges or from improper disposal of industrial wastes at landfills. TCE has been found in many drinking water supplies in the United States, including Wisconsin.

Volatile Organic Chemicals (VOCs)

VOCs can enter wells from leaking underground storage tanks, landfills, and other sources, including rainwater and melting snow.


Recreational Water Issues

Blue-Green Algae or Cyanobacteria

Wisconsin's Harmful Algal Blooms program collects information about human and animal illness and death resulting from exposure to blue-green algae. Tracking illness information will help the Wisconsin Division of Public Health measure the problem of blue-green algae in our lakes and rivers. Learn more.

Recreational Water Safety

Wisconsin is home to more than 15,000 bodies of recreational water. Being safe around these areas while you are enjoying your activities is important. Here you can learn more about safely enjoying the many recreational water activities available in Wisconsin including swimming, boating, and fishing. In addition to safety tips and information, there are materials regarding the beach monitoring done in Wisconsin to ensure your trip to the water is safe and healthy. Learn more.

Pool Licensing and Safety

Public swimming pools include but are not limited to a pool serving or installed for the state or any political subdivision of the state; a pool serving or installed at a motel, hotel, tourist rooming house, bed and breakfast establishment, campground, camp, club, association, housing development or school, or a religious, charitable, or youth organization; a mobile pool; and a pool at an educational or rehabilitative institution.

Information about public pool licensing: Restaurants, Retail Food, Lodging, and Swimming Pools questions/licensing, Department of Agriculture, Trade and Consumer Protection (DATCP).

For swimming pool safety tips in all seasons of the year, see the CDC's Healthy Swimming pages.

Campground Licensing and Safety

Information about the licensing and regulation of campgrounds: Campground questions/licensing, Department of Agriculture, Trade and Consumer Protection (DATCP).

Safety tips for swimming in lakes or rivers: CDC's Healthy Swimming: Oceans, Lakes, and Rivers.

Water-Related Emergencies

Flood Hazards and Recovery

Every year, areas of Wisconsin routinely flood. If you live or work in an area likely to flood, take some simple steps to protect yourself and your property. DHS has more information on the Flood homepage.


Drought conditions can directly affect human health. Lower levels of water in lakes and streams increase the concentration of pollutants and can lead to standing water. Droughts can also pose a risk to people who get their water from a private well. Visit the Drought homepage for more information.

Boil Water or Emergency Chlorination Notices

Fact Sheet for Private Residences P-44589 (PDF) How to keep safe if you receive a boil water notice.

Fact Sheet for Public Facilities P-45090 (PDF) How to protect customers' health during a boil water or emergency chlorination notice.

Climate and Health

Over the past 60 years, Wisconsin has become warmer and wetter, especially during the winter months. A warmer and wetter Wisconsin will affect our health. These pages provide information on Wisconsin's BRACE program and information on flooding, extreme cold and heat, and drought. Learn More.

Water Resources and Links

Specific Contaminants



  • Arsenic in Drinking Water has more information about sources of arsenic, health risks, testing, and recommendations for staying safe.


General Resources
Proper Disposal Information


Questions? Can't find what you're looking for? Contact us!

Last Revised: December 6, 2017