We read 29 results from St Charles County Pwsd 2’s 2025 water quality report. No results over a legal limit; 6 above a health goal or guideline.
Serves about 100,587 people · Water system ID MO6024530 · 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 · range 0.41 to 0.42 · Purchased water (wholesaler) · 2025 report, page 3 | 0.42 ppb | 0.004 ppb | 10 ppb | Above the health goal105x the health goal |
| Atrazinehighest measured · range ND to 0.96 · Purchased water (wholesaler) · 2025 report, page 3 | 0.96 ppb | 0.15 ppb | 3 ppb | Above the health goal6.4x the health goal |
| Gross alpha (radioactivity)highest measured · range 3.4 to 4.1 · sampled 2021 · 2025 report, page 2 | 4.1 pCi/L | 0 pCi/L | 15 pCi/L | Above the health goalThe health goal is zero |
| pHhighest measured · range 8.29 to 9.13 · sampled 2023 · 2025 report, page 4 | 9.13 | — | — | Outside the normal rangeAlkaline water can leave scale |
| Radium (combined 226 + 228)highest measured · range 1.9 to 2 · sampled 2021 · 2025 report, page 2 | 2 pCi/L | 0 pCi/L | 5 pCi/L | Above the health goalThe health goal is zero |
| Radium-226highest measured · range 1.9 to 2 · sampled 2021 · 2025 report, page 2 | 2 pCi/L | 0.05 pCi/L | 5 pCi/L | Above the health goal40x the health goal |
| Antimonyhighest measured · range 0.27 to 0.28 · Purchased water (wholesaler) · 2025 report, page 3 | 0.28 ppb | 1 ppb | 6 ppb | Below the health goal |
| Bariumhighest measured · range 0.05 to 0.1 · sampled 2023 · highest of 2 sources · 2025 report, page 2 | 0.1 ppm | 2 ppm | 2 ppm | Below the health goal |
| Chloridehighest measured · range 32.9 to 50.7 · sampled 2023 · 2025 report, page 4 | 50.7 ppm | — | 250 ppm guideline | Within the guideline |
| Chromium (total)highest measured · range 1 to 1.11 · Purchased water (wholesaler) · 2025 report, page 3 | 1.11 ppb | None set | 100 ppb | Below the legal limit |
| Copper90th percentile of homes tested, 0 over the action level · Customer taps · 2025 report, page 2 | 0.04 ppm | 0.3 ppm | 1.3 ppm (action level) | Below the health goal |
| Disinfection byproducts (HAA5)highest running annual average · range 6.4 to 22.3 · Purchased water: Distribution system, highest of 5 sources · 2025 report, page 3 | 20 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)highest running annual average · range 29.9 to 36.4 · DBPDUAL-02, highest of 5 sources · 2025 report, page 2 | 36 ppb | None set | 80 ppb | Below the legal limit |
| Fluoridehighest measured · range 0.29 to 0.95 · Purchased water (wholesaler), highest of 2 sources · 2025 report, page 3 | 0.95 ppm | 1 ppm | 4 ppm | Below the health goal |
| Ironhighest measured · range 0.01 to 0.05 · sampled 2023 · 2025 report, page 4 | 0.05 ppm | — | 0.3 ppm guideline | Within the guideline |
| Lead90th percentile of homes tested, 0 over the action level · Customer taps · 2025 report, page 2 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| Manganesehighest measured · range 0.0013 to 0.0047 · sampled 2023 · 2025 report, page 4 | 0.0047 ppm | — | 0.05 ppm guideline | Within the guideline |
| Nitrate (as N)highest measured · range 0.03 to 1.25 · highest of 2 sources · 2025 report, page 2 | 1.25 ppm | 10 ppm | 10 ppm | Below the health goal |
| Seleniumhighest measured · range 1.16 to 1.31 · Purchased water (wholesaler) · 2025 report, page 3 | 1.31 ppb | 30 ppb | 50 ppb | Below the health goal |
| Sulfatehighest measured · range 110 to 207 · sampled 2023 · 2025 report, page 4 | 207 ppm | — | 250 ppm guideline | Within the guideline |
| Total dissolved solidshighest measured · range 333 to 410 · sampled 2023 · 2025 report, page 4 | 410 ppm | — | 500 ppm guideline | Within the guideline |
| Zinchighest measured · range ND to 0.0074 · sampled 2023 · 2025 report, page 4 | 0.0074 ppm | — | 5 ppm guideline | Within the guideline |
| Alkalinityhighest measured · range 82.5 to 125 · sampled 2023 · 2025 report, page 4 | 125 ppm | None set | None | No health limit |
| Calciumhighest measured · range 23.6 to 35.6 · sampled 2023 · 2025 report, page 4 | 35.6 ppm | None set | None | No health limit |
| Hardnesshighest measured · range 8.3 to 10.8 · sampled 2023 · 2025 report, page 4 | 10.8 gpg (184 ppm) | — | — | Very hard |
| Magnesiumhighest measured · range 18.5 to 23 · sampled 2023 · 2025 report, page 4 | 23 ppm | None set | None | No health limit |
| Nickelhighest measured · range 1.38 to 2.02 · printed as 0.00202 MG/L · sampled 2023 · 2025 report, page 4 | 2.02 ppb | None set | None | No health limit |
| Potassiumhighest measured · range 4.79 to 6.24 · sampled 2023 · 2025 report, page 4 | 6.24 ppm | None set | None | No health limit |
| Sodiumhighest measured · range 46.1 to 62.9 · sampled 2023 · 2025 report, page 4 | 62.9 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. 14 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 St Charles County Pwsd 2’s water between Apr 2024 and Jan 2025. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- Lithium47.5 ppbFound in 9 of 9 samples · highest resultAbove EPA’s health reference level of 10 ppb (a guide, not a legal limit)
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.
Industrial chemicals and pesticides
Found: Atrazine
What removes it: Carbon block or RO.
Radium and uranium
Found: Gross alpha (radioactivity), Radium (combined 226 + 228), Radium-226
What removes it: Reverse osmosis.
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