We read 10 results from Town of Discovery Bay’s 2025 water quality report. No results over a legal limit; 3 above a health goal or guideline.
Serves about 16,790 people · Water system ID CA0710009 · 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 |
|---|---|---|---|---|
| Arsenicaverage · range ND to 6 · sampled 2024 · 2025 report, page 4 | 2 ppb | 0.004 ppb | 10 ppb | Above the health goal500x the health goal |
| Copper90th percentile of 30 homes tested, 0 over the action level · sampled 2024 · 2025 report, page 5 | 0.6 ppm | 0.3 ppm | 1.3 ppm (action level) | Above the health goal2x the health goal |
| Lead90th percentile of 30 homes tested, 0 over the action level · sampled 2024 · 2025 report, page 5 | 2 ppb | 0.2 ppb | 15 ppb (action level) | Above the health goal10x the health goal |
| Bariumaverage · range ND to 0.19 · sampled 2024 · 2025 report, page 4 | 0.01 ppm | 2 ppm | 2 ppm | Below the health goal |
| Chromium (total)average · range 14 to 23 · sampled 2024 · 2025 report, page 4 | 20 ppb | None set | 100 ppb | Below the legal limit |
| Fluorideaverage · range 0.2 to 0.3 · sampled 2024 · 2025 report, page 4 | 0.3 ppm | 1 ppm | 2 ppm | Below the health goal |
| pHaverage · range 7.4 to 8.5 · 2025 report, page 6 | 7.83 | — | — | Normal range |
| Alkalinityaverage · range 260 to 360 · 2025 report, page 6 | 302 ppm | None set | None | No health limit |
| Calciumaverage · range 35 to 68 · sampled 2024 · 2025 report, page 6 | 46 ppm | None set | None | No health limit |
| Magnesiumaverage · range 16 to 37 · sampled 2024 · 2025 report, page 6 | 23 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 Town of Discovery Bay’s water between Feb 2023 and Oct 2023. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- Lithium34 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.
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