We read 14 results from City of San Clemente’s 2025 water quality report. No results over a legal limit; 3 above a health goal or guideline.
Serves about 51,545 people · Water system ID CA3010036 · 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 |
|---|---|---|---|---|
| Bromateaverage · range ND to 8.4 · listed as a violation in the report · MWD Diemer plant · 2025 report, page 6 | 2.4 ppb | 0.1 ppb | 10 ppb | Above the health goal24x the health goal |
| Total dissolved solidsaverage · range 465 to 625 · listed as a violation in the report · MWD Diemer plant · 2025 report, page 6 | 545 ppm | — | 500 ppm guideline | Above the guideline1.1x the guideline (taste, odor or stains; not a health limit) |
| Uraniumaverage · range ND to 4.47 · listed as a violation in the report · printed as 1 pCi/L · MWD Diemer plant · 2025 report, page 6 | 1.49 ppb | 0.6 ppb | 30 ppb | Above the health goal2.5x the health goal |
| Bariumaverage · range 0.13 to 0.13 · listed as a violation in the report · MWD Diemer plant · 2025 report, page 6 | 0.13 ppm | 2 ppm | 2 ppm | Below the health goal |
| Chlorideaverage · range 84 to 99 · listed as a violation in the report · MWD Diemer plant · 2025 report, page 6 | 92 ppm | — | 250 ppm guideline | Within the guideline |
| Chlorineaverage · range 0.33 to 3.11 · listed as a violation in the report · Distribution system · 2025 report, page 4 | 1.86 ppm | None set | 4 ppm | Below the legal limit |
| Copper90th percentile of 30 homes tested, 0 over the action level · listed as a violation in the report · Customer taps · 2025 report, page 4 | 0.1 ppm | 0.3 ppm | 1.3 ppm (action level) | Below the health goal |
| Disinfection byproducts (HAA5)highest running annual average · range 5 to 21 · listed as a violation in the report · Distribution system · 2025 report, page 4 | 17 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)highest running annual average · range 23 to 56 · listed as a violation in the report · Distribution system · 2025 report, page 4 | 41 ppb | None set | 80 ppb | Below the legal limit |
| Fluorideaverage · range 0.45 to 1.38 · listed as a violation in the report · Distribution system · 2025 report, page 4 | 0.77 ppm | 1 ppm | 2 ppm | Below the health goal |
| Lead90th percentile of 30 homes tested, 0 over the action level · listed as a violation in the report · Customer taps · 2025 report, page 4 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| Sulfateaverage · range 146 to 218 · listed as a violation in the report · MWD Diemer plant · 2025 report, page 6 | 182 ppm | — | 250 ppm guideline | Within the guideline |
| Lithiumaverage · range 41 to 60 · sampled 2024 · MWD Diemer plant · 2025 report, page 6 | 50 ppb | None set | None | No health limit |
| Sodiumaverage · range 78 to 97 · MWD Diemer plant · 2025 report, page 6 | 88 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 City of San Clemente’s water between Jan 2024 and Oct 2024. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- Lithium60 ppbFound in 8 of 8 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.
Salty taste / high TDS
Found: Total dissolved solids
What removes it: Reverse osmosis.
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