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Water Quality Report

Jefferson, WI

Jefferson County · 7,926 residents · 1 water system

13

Contaminants detected

0

PFAS compounds

290

Hardness (mg/L)

0

Above legal limits

3

Above health guidelines

Jefferson drinking water comes from groundwater wells. Based on the most recent monitoring data, 13 contaminants have been detected in the water supply, including Lead, Nitrate, Arsenic, Copper, and 9 others. PFAS testing has been conducted with no detections. Water hardness is 290 mg/L (very hard), which can cause scale buildup in appliances and reduce soap effectiveness.

Contaminants detected in Jefferson water

Detection does not necessarily mean unsafe levels. See individual reports for concentrations and EPA limits.

Lead0.0035 / 0.015 mg/L
23% of EPA limit
Nitrate0.74 / 10 mg/L
7% of EPA limit
Arsenic0.0021 / 0.01 mg/L
21% of EPA limit
Copper120 / 1300 ug/L
9% of EPA limit
Radium4.2 / 5 pCi/L
83% of EPA limit
Uranium0.733 / 30 ug/L
2% of EPA limit
Gross Alpha Radiation9.7 / 15 pCi/L
64% of EPA limit
Total Trihalomethanes18.4 / 80 ug/L
23% of EPA limit
Haloacetic Acids (HAA5)2.8 / 60 ug/L
5% of EPA limit
Nickel0.0013 mg/L
UnregulatedInorganic
Selenium0.0068 / 0.05 mg/L
14% of EPA limit
Barium0.13 / 2 mg/L
7% of EPA limit
Fluoride0.18 / 4 mg/L
5% of EPA limit
PFAS (tested — none detected)
Microplastics (not routinely tested)

Water systems serving Jefferson

JEFFERSON WATERWORKS

7,926 servedGroundwater13 contaminants3 above guidelines
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Other cities in Jefferson County

Water quality reports for nearby Wisconsin communities.

Fort AtkinsonIxoniaJohnson CreekLake MillsPalmyraWaterlooWatertown

Frequently asked questions

Is Jefferson, WI tap water safe to drink?
Jefferson tap water meets EPA legal standards (Maximum Contaminant Levels). However, 3 contaminants are present above independent health guidelines, which are often stricter than legal limits. 13 contaminants have been detected in the water supply, including Lead, Nitrate, Arsenic, Copper, Radium. View the detailed report for each water system to see specific levels and how they compare to both legal limits and health guidelines.
What contaminants are in Jefferson water?
Monitoring has detected 13 contaminants in Jefferson's water supply: Lead, Nitrate, Arsenic, Copper, Radium, Uranium, Gross Alpha Radiation, Total Trihalomethanes, Haloacetic Acids (HAA5), Nickel, Selenium, Barium, Fluoride. 3 exceed health guidelines. See individual system reports for concentrations relative to EPA limits.
Does Jefferson water have PFAS?
Jefferson's water has been tested for PFAS compounds with no detections. Testing was conducted as part of the EPA's Unregulated Contaminant Monitoring Rule (UCMR5) program.
Is Jefferson water hard?
Yes. Jefferson water has a hardness of 290 mg/L (very hard). Hard water is not a health concern but can cause scale buildup in water heaters and appliances, reduce soap effectiveness, and leave mineral deposits. Water softeners or conditioning systems can address hardness.
Where does Jefferson get its drinking water?
Jefferson'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. Jefferson is served by one water system: JEFFERSON WATERWORKS.

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