We read 5 results from City of Lathrop’s 2025 water quality report. No results over a legal limit or above a health goal.
Serves about 35,080 people · Water system ID CA3910015 · 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 |
|---|---|---|---|---|
| Chlorineaverage · range 0.1 to 1.4 · listed as a violation in the report · Distribution system · 2025 report, page 5 | 0.9 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 · sampled 2024 · Customer taps · 2025 report, page 6 | 0.13 ppm | 0.3 ppm | 1.3 ppm (action level) | Below the health goal |
| Disinfection byproducts (HAA5)highest running annual average · range 10 to 40 · listed as a violation in the report · Distribution system · 2025 report, page 5 | 29 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)highest running annual average · range 19 to 49 · listed as a violation in the report · Distribution system · 2025 report, page 5 | 33 ppb | None set | 80 ppb | Below the legal limit |
| Lead90th percentile of 30 homes tested, 0 over the action level · listed as a violation in the report · sampled 2024 · Customer taps · 2025 report, page 6 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
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 Lathrop’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.
- PFOS17 pptFound in 2 of 6 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
- PFHxS3.5 pptFound in 1 of 6 samples · highest resultNo federal limit in force for this one
- PFBS5 pptFound in 2 of 6 samples · highest resultNo federal limit in force for this one
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: PFOS (EPA testing)
What removes it: Reverse osmosis.
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