We read 12 results from San Jose Water’s 2025 water quality report. No results over a legal limit or above a health goal.
Serves about 1,039,920 people · Water system ID CA4310011 · 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 |
|---|---|---|---|---|
| Chloraminehighest running annual average · Distribution system · 2025 report, page 6 | 1.42 ppm | None set | 4 ppm | Below the legal limit |
| Chlorideaverage · range 23 to 67 · Valley Water surface water, highest of 3 sources · 2025 report, page 7 | 53 ppm | — | 250 ppm guideline | Within the guideline |
| Disinfection byproducts (HAA5)highest site average · range 1.4 to 32.8 · Distribution system · 2025 report, page 6 | 27.3 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)highest site average · Distribution system · 2025 report, page 6 | 47.7 ppb | None set | 80 ppb | Below the legal limit |
| Ironaverage · range ND to 0.29 · printed as ND ppb · Groundwater · 2025 report, page 7 | Not detected | — | 0.3 ppm guideline | Not detected |
| Lead90th percentile of homes tested · Customer taps (2025, about 100 homes per round) · 2025 report, page 12 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| Manganeseaverage · range 0.005 to 0.01 · printed as 9 ppb · Valley Water surface water, highest of 2 sources · 2025 report, page 7 | 0.009 ppm | — | 0.05 ppm guideline | Within the guideline |
| Sulfateaverage · range 29 to 63 · Valley Water surface water, highest of 3 sources · 2025 report, page 7 | 49 ppm | — | 250 ppm guideline | Within the guideline |
| Total dissolved solidsaverage · range 290 to 520 · Groundwater, highest of 3 sources · 2025 report, page 7 | 397 ppm | — | 500 ppm guideline | Within the guideline |
| Boronaverage · range ND to 0.15 · printed as 112 ppb · Groundwater · 2025 report, page 7 | 0.11 ppm | None set | None | No health limit |
| Hardnessaverage · range 10.2 to 26.4 · Groundwater, highest of 3 sources · 2025 report, page 7 | 16.8 gpg (288 ppm) | — | — | Very hard |
| Sodiumaverage · range 25 to 56 · Valley Water surface water, highest of 3 sources · 2025 report, page 7 | 48 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 San Jose Water’s water between Feb 2023 and Feb 2025. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- PFOS6.2 pptFound in 2 of 37 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
- PFHxS5.5 pptFound in 12 of 36 samples · highest resultNo federal limit in force for this one
- Lithium10 ppbFound in 5 of 41 samples · highest resultBelow EPA’s health reference level of 10 ppb
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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