We read 10 results from City of Mercedes’s 2025 water quality report. No results over a legal limit; 4 above a health goal or guideline.
Serves about 16,258 people · Water system ID TX1080007 · 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 homes tested, 0 over the action level · 2025 report, page 2 | 0.43 ppm | 0.3 ppm | 1.3 ppm (action level) | Above the health goal1.4x the health goal |
| Gross alpha (radioactivity)single sample · sampled 2023 · 2025 report, page 2 | 3.3 pCi/L | 0 pCi/L | 15 pCi/L | Above the health goalThe health goal is zero |
| Gross beta (radioactivity)single sample · sampled 2023 · 2025 report, page 2 | 7.5 pCi/L | 0 pCi/L | 50 pCi/L | Above the health goalThe health goal is zero |
| Lead90th percentile of homes tested, 0 over the action level · printed as .0040 ppm · 2025 report, page 2 | 4 ppb | 0.2 ppb | 15 ppb (action level) | Above the health goal20x the health goal |
| Chloraminehighest running annual average · range 0.5 to 4.3 · 2025 report, page 2 | 2.18 ppm | None set | 4 ppm | Below the legal limit |
| Disinfection byproducts (HAA5)highest running annual average · range 7.2 to 23.4 · 2025 report, page 2 | 16.1 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)highest running annual average · range 20.9 to 71.6 · 2025 report, page 2 | 51.4 ppb | None set | 80 ppb | Below the legal limit |
| Nitrate (as N)highest measured · 2025 report, page 2 | 0.61 ppm | 10 ppm | 10 ppm | Below the health goal |
| Lithiumaverage · range 49.6 to 61.4 · sampled 2023 · 2025 report, page 1 | 56 ppb | None set | None | No health limit |
| PFHxA (a PFAS)single sample · printed as 0.0033 ppb · sampled 2023 · 2025 report, page 2 | 3.3 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.
EPA testing for PFAS and lithium
EPA’s own nationwide testing (UCMR 5) found these in City of Mercedes’s water between Jan 2023 and Oct 2023. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- Lithium61.4 ppbFound in 4 of 4 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.
Lead
Found: Copper, Lead
What removes it: Reverse osmosis or Certified carbon block or RO.
Radium and uranium
Found: Gross alpha (radioactivity), Gross beta (radioactivity)
What removes it: Reverse osmosis.
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