We read 17 results from City of Los Banos’s 2025 water quality report. No results over a legal limit; 5 above a health goal or guideline.
Serves about 47,419 people · Water system ID CA2410005 · 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 |
|---|---|---|---|---|
| Arsenicaverage · range 5.7 to 9.2 · sampled 2023 · Wells · 2025 report, page 4 | 6.7 ppb | 0.004 ppb | 10 ppb | Above the health goal1,675x the health goal |
| Copper90th percentile of 30 homes tested, 0 over the action level · sampled 2023 · Customer taps · 2025 report, page 7 | 0.32 ppm | 0.3 ppm | 1.3 ppm (action level) | Above the health goal1.1x the health goal |
| Tetrachloroethylene (PCE)average · range ND to 0.55 · sampled 2023 · Wells · 2025 report, page 6 | 0.42 ppb | 0.06 ppb | 5 ppb | Above the health goal7x the health goal |
| Total dissolved solidsaverage · range 480 to 1,400 · sampled 2023 · Wells · 2025 report, page 7 | 723 ppm | — | 500 ppm guideline | Above the guideline1.4x the guideline (taste, odor or stains; not a health limit) |
| Uraniumaverage · range ND to 23.8 · printed as 1.2 pCi/L · sampled 2020 · Wells · 2025 report, page 6 | 1.79 ppb | 0.6 ppb | 30 ppb | Above the health goal3x the health goal |
| Bariumaverage · range ND to 0.12 · sampled 2023 · Wells · 2025 report, page 4 | 0.08 ppm | 2 ppm | 2 ppm | Below the health goal |
| Chlorideaverage · range 92 to 340 · sampled 2023 · Wells · 2025 report, page 7 | 143 ppm | — | 250 ppm guideline | Within the guideline |
| Chlorineaverage · range 0.5 to 0.76 · Distribution system · 2025 report, page 4 | 0.62 ppm | None set | 4 ppm | Below the legal limit |
| Chromium (total)average · range 19 to 43 · sampled 2023 · Wells · 2025 report, page 4 | 30.9 ppb | None set | 100 ppb | Below the legal limit |
| Disinfection byproducts (HAA5)average · range 3 to 5 · sampled 2024 · Distribution system · 2025 report, page 4 | 4 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)average · range 7.9 to 17 · sampled 2024 · Distribution system · 2025 report, page 4 | 12.5 ppb | None set | 80 ppb | Below the legal limit |
| Fluorideaverage · range ND to 0.13 · Wells · 2025 report, page 4 | 0.1 ppm | 1 ppm | 2 ppm | Below the health goal |
| Lead90th percentile of 30 homes tested, 0 over the action level · sampled 2023 · Customer taps · 2025 report, page 7 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| Nitrate (as N)average · range 2.6 to 9.9 · Wells · 2025 report, page 4 | 5.72 ppm | 10 ppm | 10 ppm | Below the health goal |
| Sulfateaverage · range 54 to 400 · sampled 2023 · Wells · 2025 report, page 7 | 138 ppm | — | 250 ppm guideline | Within the guideline |
| Hardnessaverage · range 13.5 to 43.3 · sampled 2023 · Wells · 2025 report, page 7 | 20.2 gpg (346 ppm) | — | — | Very hard |
| Sodiumaverage · range 49 to 210 · sampled 2023 · Wells · 2025 report, page 7 | 96 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.
EPA testing for PFAS and lithium
EPA’s own nationwide testing (UCMR 5) found these in City of Los Banos’s water between Sep 2024 and Mar 2025. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- Lithium43.6 ppbFound in 26 of 26 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.
Copper
Found: Copper
What removes it: Reverse osmosis.
Industrial chemicals and pesticides
Found: Tetrachloroethylene (PCE)
What removes it: Carbon block or RO.
Salty taste / high TDS
Found: Total dissolved solids
What removes it: Reverse osmosis.
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