We read 12 results from Northfield’s 2025 water quality report. No results over a legal limit; 3 above a health goal or guideline.
Serves about 20,790 people · Water system ID MN1660010 · Read the district’s 2025 report (opens in a new tab)
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Results from the 2025 report
Each number is copied from the district’s report and links to the page it’s printed on. Where the report lists several plants, wells or purchased water, the highest is shown.
| Contaminant | Result | Health goal | Legal limit | What it means |
|---|---|---|---|---|
| Copper90th percentile of 30 homes tested, 0 over the action level · Customer taps · 2025 report, page 3 | 0.69 ppm | 0.3 ppm | 1.3 ppm (action level) | Above the health goal2.3x the health goal |
| Gross alpha (radioactivity)highest measured · range 6.1 to 14 · Wells / treated water · 2025 report, page 4 | 14 pCi/L | 0 pCi/L | 15 pCi/L | Above the health goalThe health goal is zero |
| Radium (combined 226 + 228)highest measured · range ND to 1.5 · Wells / treated water · 2025 report, page 4 | 1.5 pCi/L | 0 pCi/L | 5 pCi/L | Above the health goalThe health goal is zero |
| Bariumhighest measured · Wells / treated water · 2025 report, page 4 | 0.03 ppm | 2 ppm | 2 ppm | Below the health goal |
| Chlorinehighest running annual average · range 0.28 to 0.51 · Distribution system · 2025 report, page 4 | 0.4 ppm | None set | 4 ppm | Below the legal limit |
| Disinfection byproducts (HAA5)highest running annual average · range ND to 1.7 · Distribution system · 2025 report, page 4 | 1.7 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)highest running annual average · range 7.9 to 18.3 · Distribution system · 2025 report, page 4 | 18.3 ppb | None set | 80 ppb | Below the legal limit |
| Fluoridehighest running annual average · range 0.55 to 0.61 · Wells / treated water · 2025 report, page 5 | 0.58 ppm | 1 ppm | 4 ppm | Below the health goal |
| Nitrate (as N)highest measured · range ND to 4 · Wells / treated water · 2025 report, page 4 | 4 ppm | 10 ppm | 10 ppm | Below the health goal |
| Lithiumhighest measured · range ND to 9.2 · sampled 2024 · Wells / treated water · 2025 report, page 7 | 9.2 ppb | None set | None | No health limit |
| PFBA (a PFAS)as reported · range 1.8 to 20 · Wells / treated water · 2025 report, page 7 | 8.48 ppt | None set | None | No health limit |
| PFBS (a PFAS)as reported · range ND to 0.83 · Wells / treated water · 2025 report, page 7 | 0.42 ppt | None set | None | No health limit |
Utility results describe the whole system, measured where water enters the pipes, not your tap. Your home’s plumbing can add lead or copper. 3 numbers we weren’t sure about are held back until a person checks.
EPA testing for PFAS and lithium
EPA’s own nationwide testing (UCMR 5) found these in Northfield’s water between Aug 2023 and May 2024. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- Lithium9.2 ppbFound in 1 of 10 samples · highest resultBelow EPA’s health reference level of 10 ppb
Source: EPA UCMR 5 occurrence data. The highest single result is shown; one high sample doesn’t mean every glass is that high.
What you can do
Nothing here is an emergency notice: if the district has a violation, it must tell customers directly. If you’d like to lower these at your tap, these are the treatments that remove them, and the catalog shows the models certified for each. Ranking is by certified removal; commissions never change the order.
Copper
Found: Copper
What removes it: Reverse osmosis.
Radium and uranium
Found: Gross alpha (radioactivity), Radium (combined 226 + 228)
What removes it: Reverse osmosis.
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