We read 6 results from Los Osos Community Services District’s 2025 water quality report. No results over a legal limit or above a health goal.
Serves about 7,086 people · Water system ID CA4010016 · 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 |
|---|---|---|---|---|
| Arsenicas reported · sampled 2022 · 2025 report, page 5 | Not detected | 0.004 ppb | 10 ppb | Not detected |
| Chlorideas reported · range 28.1 to 184 · 2025 report, page 7 | 61 ppm | — | 250 ppm guideline | Within the guideline |
| Disinfection byproducts (TTHM)as reported · sampled 2022 · 2025 report, page 6 | Not detected | None set | 80 ppb | Not detected |
| Ironas reported · range ND to 0.14 · printed as 63 ppb · sampled 2024 · 2025 report, page 7 | 0.06 ppm | — | 0.3 ppm guideline | Within the guideline |
| Sulfateas reported · range 8 to 47 · sampled 2023 · 2025 report, page 7 | 15 ppm | — | 250 ppm guideline | Within the guideline |
| Nickelas reported · sampled 2022 · 2025 report, page 6 | Not detected | 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. 2 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 Los Osos Community Services District’s water between Jan 2024 and Jul 2024. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- PFOA14.7 pptFound in 3 of 14 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
- PFOS11.7 pptFound in 1 of 14 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
- PFHxS8.4 pptFound in 1 of 14 samples · highest resultNo federal limit in force for this one
- PFBS18 pptFound in 3 of 14 samples · highest resultNo federal limit in force for this one
- Lithium16.1 ppbFound in 5 of 14 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.
PFAS ("forever chemicals")
Found: PFOA (EPA testing), PFOS (EPA testing)
What removes it: Reverse osmosis.
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