Community Water Systems Drinking Water Quality

Dataset: Drinking Water Quality

Minnesota has about 960 community water systems (CWS) that serve approximately 80% of Minnesota residents. Water from these systems can come from groundwater (water found in underground aquifers: the pores between sand, clay, and rock)) or from surface sources (rivers, lakes, and streams). You can find your community water system information in the annual Consumer Confidence Report (CCR). Find your CCR.

- Arsenic (mean)
- Arsenic (max)
- HAA (mean)
- HAA (max)
- Nitrate (mean)
- Nitrate (max)
- Radium (mean)
- Radium (max)
- TCE (mean)
- TCE (max)
- TTHM (mean)
- TTHM (max)
- PCE (mean)
- PCE (max)
- Uranium (mean)
- Uranium (max)

Mean arsenic levels of Minnesota community water systems

Very few community water systems provide drinking water with levels of arsenic above the federal drinking water standard. Read the most recent Drinking Water Protection Annual Reportfor more information.

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Source: Minnesota Drinking Water Information System (MNDWIS). Concentrations are the mean annual levels for community water systems in Minnesota.

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Maximum arsenic levels of Minnesota community water systems

All community water systems test for arsenic and ensure levels meet the Environmental Protection Agency drinking water standard, or Maximum Contaminant Level (MCL). The MCL for arsenic is 10 micrograms per liter (µg/L). The maximum value of each system shows the highest concentration in any single sample, prior to any blending of water. The level of arsenic that reaches the consumer's tap may be lower - learn more about arsenic in drinking water.

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). Concentrations are the maximum annual levels for community water systems in Minnesota.

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Mean HAA5 levels of Minnesota community water systems

All community water systems that disinfect test for HAA5s and ensure levels meet the Environmental Protection Agency drinking water standard, or Maximum Contaminant Level (MCL). The MCL for HAA5 is 60 µg/L. This MCL is for five HAA5s added together.

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). Concentrations are the mean annual levels for community water systems in Minnesota.

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Maximum HAA5 levels of Minnesota community water systems

This chart shows the percent of systems by annual maximum HAA5 concentration. In this chart, the maximum value reflects the sample with the highest concentration at a single sampling location. The level of HAA5 in water that ultimately reaches the consumer's tap may be different. For more information on DBPs, see Disinfection and Disinfection Byproducts.

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). Concentrations are the maximum annual levels for community water systems in Minnesota.

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Mean nitrate levels of Minnesota community water systems

Nitrate has been detected in surface water and groundwater in many places in Minnesota. Both land use and hydrogeology affect the levels of nitrate in water. Community public water systems with elevated nitrate levels (above 3 mg/L) tend to be in southwestern, southeastern, central, and north-central areas of the state.

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). Concentrations are the mean annual levels for community water systems in Minnesota.

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Maximum nitrate levels of Minnesota community water systems

The chart above shows the percent of systems by annual maximum concentration. A system may have a number of different entry points to the distribution system. In this case, the maximum value reflects the highest concentration in any single sample, prior to any blending of water. For more information, including how MDH works with systems to prevent and respond to nitrate issues, see MDH Source Water Protection and Nitrate in Drinking Water.

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). Concentrations are the maximum annual levels for community water systems in Minnesota.

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Mean radium levels in Minnesota community water systems

Radium is a type of radionuclide (radioactive material). Radionuclides from naturally occurring sources, like rocks and soil, can get into groundwater and surface waters in Minnesota. All community water systems test for radium and ensure levels meet the Environmental Protection Agency drinking water standard, or Maximum Contaminant Level (MCL). Radium and other levels of radioactivity in water are measured in picocuries per liter (pCi/L) of water.

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). The federal Maximum Contaminant Level (MCL) for radium is 5 picocuries per liter (pCi/L). Concentrations are the mean annual levels for community water systems in Minnesota

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Maximum radium levels of Minnesota community water systems

MDH studies found that the highest levels of radionuclides (radium and other radioactive materials) in source water occur in the Mount Simon-Hinckley and Jordan Aquifers in southeastern Minnesota. Treatment is required in communities with source water radionuclides levels greater than 5 pCi/L.

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). The federal Maximum Contaminant Level (MCL) for radium is 5 picocuries per liter (pCi/L). Concentrations are the maximum annual levels for community water systems in Minnesota

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Mean PCE levels of Minnesota community water systems

Tetrachloroethylene (PCE) is a solvent used in industrial processes, metal cleaning, dry-cleaning, and textile processing. Spills and improper disposal of PCE have resulted in contamination of groundwater at several locations in Minnesota.

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Source: Minnesota Drinking Water Information System (MNDWIS). The federal Maximum Contaminant Level (MCL) for PCE is 5 µg/L. Concentrations are the mean annual levels for community water systems in Minnesota.

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Maximum PCE levels of Minnesota community water systems

Drinking water with PCE at levels lower than the MCL may increase the risk of adverse health effects for some people. Learn more about PCE

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). The federal Maximum Contaminant Level (MCL) for PCE is 5 µg/L. Concentrations are the maximum annual levels for community water systems in Minnesota.

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Mean TTHM levels of Minnesota Community Water Systems

All community water systems that disinfect test for TTHMs and ensure levels meet the Environmental Protection Agency drinking water standard, or Maximum Contaminant Level (MCL).

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). The federal Maximum Contaminant Level (MCL) for TTHMs is 80 µg/L. Concentrations are the mean annual levels for community water systems in Minnesota.

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Maximum TTHM levels of Minnesota Community Water Systems

A system may have a number of different locations in the distribution system with different levels of TTHMs. In this chart, the maximum value reflects the sample with the highest concentration at a single location. The level of TTHMs in the water that reaches a consumer's tap is typically lower due to blending.For more information on DBPs, see Disinfection and Disinfection Byproducts.

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). The federal Maximum Contaminant Level (MCL) for TTHMs is 80 µg/L. Concentrations are the maximum annual levels for community water systems in Minnesota.

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Mean TCE levels of Minnesota community water systems

Trichloroethylene (TCE) is a common environmental contaminant that dissolves in water and readily evaporates from soil and water into the air. If spilled on the ground, TCE can move through soil and into groundwater where it may pollute private and public drinking water wells.

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). The federal Maximum Contaminant Level (MCL) is 5 µg/L. Concentrations are the mean annual levels for community water systems in Minnesota.

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Maximum TCE levels of Minnesota community water systems

The maximum contaminant level (MCL) for TCE is 5 micrograms per liter of drinking water (µg/L). Maximum Contaminant Levels (MCLs) are set by the United States Environmental Protection Agency (US EPA) and enforced by Minnesota Department of Health (MDH).

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). Concentrations are the maximum annual levels for community water systems in Minnesota.

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Mean uranium levels in Minnesota community water systems

Uranium is a type of radionuclide (radioactive material). Radionuclides from naturally occurring sources, like rocks and soil, can get into groundwater and surface waters in Minnesota.

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). The federal Maximum Contaminant Level (MCL) for uranium is 20 picocuries per liter (pCi/L). Concentrations are the mean annual levels for community water systems in Minnesota

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Maximum uranium levels in Minnesota community water systems

Community water systems that test for uranium ensure that levels meet the Environmental Protection Agency drinking water standard, or Maximum Contaminant Level (MCL). Uranium and other levels of radioactivity in water are measured in picocuries per liter (pCi/L) of water.

Tip: Double-click a legend item to display only the selected concentration. Double-click again to reset the chart.

Source: Minnesota Drinking Water Information System (MNDWIS). The federal Maximum Contaminant Level (MCL) for uranium is 20 picocuries per liter (pCi/L). Concentrations are the maximum annual levels for community water systems in Minnesota

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Water system sources
- Mean nitrate
- Mean HAA
- Mean TTHM
- Mean TCE
- Mean PCE
- Mean arsenic
- Mean radium
- Mean uranium

Community Water System Sources, 2025

Minnesota has community water systems (CWS) that serve approximately 80% of Minnesota residents. Though most systems use groundwater (underground aquifers tapped by wells), about one-fourth of the state's residents drink water that comes from surface water systems (rivers, lakes, and streams).

Source: Minnesota Drinking Water Information System (MNDWIS). Water systems are mapped to their general vicinity, not actual coordinates

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Community water systems: mean nitrate, 2025

Source: Minnesota Drinking Water Information System (MNDWIS). Water systems are mapped to their general vicinity, not actual coordinates. Not all water systems are tested annually for every contaminant -- water systems that did not undergo testing for nitrate in 2025 are not displayed

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Community water systems: mean haloacetic acids (HAA), 2025

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Community water systems: mean total trihalomethanes (TTHM), 2025

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Community water systems: mean trichloroethylene (TCE), 2025

Source: Minnesota Drinking Water Information System (MNDWIS). Water systems are mapped to their general vicinity, not actual coordinates. Water systems that did not undergo testing for TCE in 2025 are not displayed

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Community water systems: mean tetrachloroethylene (PCE), 2025

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Community water systems: mean arsenic, 2025

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Community water systems: mean radium, 2025

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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Community water systems: mean uranium, 2025

Display ID	Topic	Dataset	Contaminant	Year	Month	Geography	Geo ID	Geo Name	Variable	Water Source	Value	Measure	Upper CL	Lower CL	Count	Population	Note	Label	Max_Concentration	County	City

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