We read 18 results from Ann Arbor’s 2025 water quality report. No results over a legal limit; 6 above a health goal or guideline.
Serves about 118,017 people · Water system ID MI0000220 · 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 |
|---|---|---|---|---|
| Arsenichighest measured · listed as a violation in the report · Treated water · 2025 report | 3.9 ppb | 0.004 ppb | 10 ppb | Above the health goal975x the health goal |
| Bromatehighest running annual average · range ND to 8.6 · listed as a violation in the report · Treatment plant · 2025 report | 4 ppb | 0.1 ppb | 10 ppb | Above the health goal40x the health goal |
| Gross alpha (radioactivity)single sample · listed as a violation in the report · sampled 2023 · Treated water · 2025 report | 3.75 pCi/L | 0 pCi/L | 15 pCi/L | Above the health goalThe health goal is zero |
| Lead90th percentile of 61 homes tested, 1 over the action level · listed as a violation in the report · sampled 2023 · Customer taps (61 sites) · 2025 report | 2 ppb | 0.2 ppb | 15 ppb (action level) | Above the health goal10x the health goal |
| Radium (combined 226 + 228)single sample · listed as a violation in the report · sampled 2020 · Treated water · 2025 report | 2 pCi/L | 0 pCi/L | 5 pCi/L | Above the health goalThe health goal is zero |
| Total coliform bacteriahighest month · range ND to 0.8 · listed as a violation in the report · Distribution system · 2025 report | 0.8 % positive | 0 % positive | 5 % positive | Above the health goalThe health goal is zero |
| Bariumhighest measured · listed as a violation in the report · printed as 88 ppb · Treated water · 2025 report | 0.09 ppm | 2 ppm | 2 ppm | Below the health goal |
| Chloraminehighest running annual average · range 0.9 to 3.4 · listed as a violation in the report · Distribution system · 2025 report | 2.5 ppm | None set | 4 ppm | Below the legal limit |
| Copper90th percentile of 61 homes tested, 0 over the action level · listed as a violation in the report · printed as 100 ppb · sampled 2023 · Customer taps (61 sites) · 2025 report | 0.1 ppm | 0.3 ppm | 1.3 ppm (action level) | Below the health goal |
| Disinfection byproducts (HAA5)highest running annual average · range ND to 10.3 · listed as a violation in the report · Distribution system · 2025 report | 12 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)highest running annual average · range 2.6 to 9.2 · listed as a violation in the report · Distribution system · 2025 report | 6 ppb | None set | 80 ppb | Below the legal limit |
| Fluoridehighest measured · range ND to 0.82 · listed as a violation in the report · Treated water · 2025 report | 0.82 ppm | 1 ppm | 4 ppm | Below the health goal |
| Nitrate (as N)highest measured · range ND to 1.1 · listed as a violation in the report · Treated water · 2025 report | 1.1 ppm | 10 ppm | 10 ppm | Below the health goal |
| Perchlorateaverage · Treated water · 2025 report | 0.26 ppb | 1 ppb | 6 ppb | Below the health goal |
| Total dissolved solidsaverage · range 276 to 406 · Treated water · 2025 report | 351 ppm | — | 500 ppm guideline | Within the guideline |
| Turbidity (cloudiness)highest measured · listed as a violation in the report · Treatment plant · 2025 report | 0.2 NTU | None set | 1 NTU | Below the legal limit |
| Hardnessaverage · range 4.33 to 10.5 · Treated water · 2025 report | 7.37 gpg (126 ppm) | — | — | Hard |
| Sodiumaverage · range 59 to 96 · Treated water · 2025 report | 71 ppm | 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.
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.
Radium and uranium
Found: Gross alpha (radioactivity), Radium (combined 226 + 228)
What removes it: Reverse osmosis.
Lead
Found: Lead
What removes it: Certified carbon block or RO.
Bacteria and viruses
Found: Total coliform bacteria
What removes it: UV purification (and tell your utility).
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