We read 12 results from City of Napa’s 2025 water quality report. No results over a legal limit; 2 above a health goal or guideline.
Serves about 84,804 people · Water system ID CA2810003 · 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 |
|---|---|---|---|---|
| Chromium-6average · range 0.09 to 0.13 · Treatment plants · 2025 report, page 4 | 0.11 ppb | 0.02 ppb | 10 ppb | Above the health goal5.5x the health goal |
| Copper90th percentile of 35 homes tested, 0 over the action level · sampled 2024 · Customer taps · 2025 report, page 4 | 0.49 ppm | 0.3 ppm | 1.3 ppm (action level) | Above the health goal1.6x the health goal |
| Chlorideaverage · range 9 to 14 · Treatment plants · 2025 report, page 5 | 11.5 ppm | — | 250 ppm guideline | Within the guideline |
| Chlorinehighest running annual average · range 0.01 to 1.59 · Distribution system · 2025 report, page 4 | 0.67 ppm | None set | 4 ppm | Below the legal limit |
| Disinfection byproducts (HAA5)highest running annual average · range 17 to 103 · Distribution system · 2025 report, page 4 | 56.6 ppb | None set | 60 ppb | Below the legal limit |
| Lead90th percentile of 35 homes tested, 0 over the action level · sampled 2024 · Customer taps · 2025 report, page 4 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| Sulfateaverage · range 43 to 58 · Treatment plants · 2025 report, page 5 | 51 ppm | — | 250 ppm guideline | Within the guideline |
| Total dissolved solidsaverage · range 127 to 188 · Treatment plants · 2025 report, page 5 | 156 ppm | — | 500 ppm guideline | Within the guideline |
| Turbidity (cloudiness)highest measured · Treatment plants · 2025 report, page 4 | 0.49 NTU | None set | 1 NTU | Below the legal limit |
| Boronaverage · range ND to 0.11 · printed as 53 ppb · Treatment plants · 2025 report, page 5 | 0.05 ppm | None set | None | No health limit |
| Hardnessaverage · range 4.62 to 8.3 · Treatment plants · 2025 report, page 5 | 6.49 gpg (111 ppm) | — | — | Moderately hard |
| Sodiumaverage · range 16 to 22 · Treatment plants · 2025 report, page 5 | 19 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. 2 numbers we weren’t sure about are held back until a person checks.
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.
Copper
Found: Copper
What removes it: Reverse osmosis.
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