We read 15 results from Mo American St Louis St Charles Counties’s 2025 water quality report. No results over a legal limit; 3 above a health goal or guideline.
Serves about 1,100,000 people · Water system ID MO6010716 · 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 |
|---|---|---|---|---|
| Atrazinehighest measured · range ND to 0.3 · Entry points · 2025 report, page 2 | 0.3 ppb | 0.15 ppb | 3 ppb | Above the health goal2x the health goal |
| Gross alpha (radioactivity)highest measured · range ND to 3.4 · sampled 2024 · Entry points · 2025 report, page 3 | 3.4 pCi/L | 0 pCi/L | 15 pCi/L | Above the health goalThe health goal is zero |
| Total coliform bacteriahighest month · Distribution system · 2025 report, page 3 | 0.32 % positive | 0 % positive | 5 % positive | Above the health goalThe health goal is zero |
| Chloridehighest measured · range 17.6 to 34.6 · Entry points · 2025 report, page 3 | 34.6 ppm | — | 250 ppm guideline | Within the guideline |
| Copper90th percentile of homes tested, 0 over the action level · Customer taps · 2025 report, page 2 | Not detected | 0.3 ppm | 1.3 ppm (action level) | Not detected |
| Disinfection byproducts (HAA5)highest running annual average · range 4 to 31.3 · Distribution system (18 sites) · 2025 report, page 2 | 29 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)highest running annual average · range 1.6 to 50.2 · Distribution system (18 sites) · 2025 report, page 2 | 47 ppb | None set | 80 ppb | Below the legal limit |
| Fluoridehighest measured · range 0.49 to 0.59 · Entry points · 2025 report, page 2 | 0.59 ppm | 1 ppm | 4 ppm | Below the health goal |
| 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 |
| Nitrate (as N)highest measured · range 0.56 to 1.1 · Entry points · 2025 report, page 2 | 1.1 ppm | 10 ppm | 10 ppm | Below the health goal |
| Sulfatehighest measured · range 9.9 to 101 · Entry points · 2025 report, page 3 | 101 ppm | — | 250 ppm guideline | Within the guideline |
| Turbidity (cloudiness)highest measured · Treatment plants (highest of 5) · 2025 report, page 3 | 0.16 NTU | None set | 1 NTU | Below the legal limit |
| Alkalinityhighest measured · range 129 to 200 · Entry points · 2025 report, page 3 | 200 ppm | None set | None | No health limit |
| Chloratehighest measured · range 60 to 430 · printed as 0.43 MG/L · Entry points (UCMR) · 2025 report, page 3 | 430 ppb | None set | None | No health limit |
| Sodiumhighest measured · range 9.2 to 37.3 · Entry points · 2025 report, page 3 | 37.3 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.
EPA testing for PFAS and lithium
EPA’s own nationwide testing (UCMR 5) found these in Mo American St Louis St Charles Counties’s water between Mar 2024 and Dec 2024. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- Lithium86.8 ppbFound in 16 of 24 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)
What removes it: Reverse osmosis.
Bacteria and viruses
Found: Total coliform bacteria
What removes it: UV purification (and tell your utility).
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