Water Quality Report
Colby, WI
Marathon County · 1,829 residents · 1 water system
12
Contaminants detected
4
PFAS compounds
—
Hardness (mg/L)
1
Above legal limits
1
Above health guidelines
Colby drinking water comes from groundwater wells. Based on the most recent monitoring data, 12 contaminants have been detected in the water supply, including Lead, Nitrate, Copper, Radium, and 8 others. PFAS compounds have been detected at trace levels in Colby water.
Contaminants detected in Colby water
Detection does not necessarily mean unsafe levels. See individual reports for concentrations and EPA limits.
Lead0.00095 / 0.015 mg/L
6% of EPA limit
Nitrate4.3 / 10 mg/L
43% of EPA limit
Copper160 / 1300 ug/L
12% of EPA limit
Radium1.6 / 5 pCi/L
32% of EPA limit
Uranium38 / 30 ug/L
127% of EPA limit
Gross Alpha Radiation10.2 / 15 pCi/L
68% of EPA limit
Total Trihalomethanes15.9 / 80 ug/L
20% of EPA limit
Haloacetic Acids (HAA5)2 / 60 ug/L
3% of EPA limit
Nickel0.0011 mg/L
UnregulatedInorganic
Fluoride0.72 / 4 mg/L
18% of EPA limit
Dichlorodifluoromethane0.54 ug/L
UnregulatedVOC
Barium0.07 / 2 mg/L
4% of EPA limit
PFAS (4 compounds detected)
Microplastics (not routinely tested)
Water systems serving Colby
Other cities in Marathon County
Water quality reports for nearby Wisconsin communities.
Frequently asked questions
Is Colby, WI tap water safe to drink?
Colby tap water has 1 contaminant currently measured above EPA legal standards (Maximum Contaminant Levels), and 1 above independent health guidelines. 12 contaminants have been detected in the water supply, including Lead, Nitrate, Copper, Radium, Uranium. View the detailed report for each water system to see specific levels, how they compare to both legal limits and health guidelines, and what actions to take.
What contaminants are in Colby water?
Monitoring has detected 12 contaminants in Colby's water supply: Lead, Nitrate, Copper, Radium, Uranium, Gross Alpha Radiation, Total Trihalomethanes, Haloacetic Acids (HAA5), Nickel, Fluoride, Dichlorodifluoromethane, Barium. Additionally, 4 PFAS compounds have been detected at trace levels. 1 of these are above EPA legal limits. 1 exceed health guidelines. See individual system reports for concentrations relative to EPA limits.
Does Colby water have PFAS?
Yes. 4 PFAS compounds have been detected in Colby's water supply at trace levels. PFAS are sometimes called "forever chemicals" because they do not break down in the environment. The EPA has set Maximum Contaminant Levels for several PFAS compounds. View the detailed report for specific concentrations.
Where does Colby get its drinking water?
Colby's drinking water comes from groundwater wells that draw from underground aquifers. The water is treated and tested according to Wisconsin DNR and EPA requirements before distribution. Colby is served by one water system: COLBY WATERWORKS.
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