We read 20 results from City of Manteca’s 2025 water quality report. No results over a legal limit; 4 above a health goal or guideline.
Serves about 84,928 people · Water system ID CA3910005 · 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 ND to 13.6 · Groundwater wells · 2025 report, page 3 | 4.9 ppb | 0.004 ppb | 10 ppb | Above the health goal1,225x the health goal |
| Chromium-6average · range ND to 4.3 · Groundwater wells · 2025 report, page 3 | 2.4 ppb | 0.02 ppb | 10 ppb | Above the health goal120x the health goal |
| Gross alpha (radioactivity)average · range ND to 14.6 · Groundwater wells · 2025 report, page 3 | 4.2 pCi/L | 0 pCi/L | 15 pCi/L | Above the health goalThe health goal is zero |
| Uraniumaverage · range ND to 15.2 · printed as 4.4 pCi/L · Groundwater wells · 2025 report, page 3 | 6.56 ppb | 0.6 ppb | 30 ppb | Above the health goal11x the health goal |
| Bariumaverage · range ND to 0.2 · Groundwater wells · 2025 report, page 3 | 0.1 ppm | 2 ppm | 2 ppm | Below the health goal |
| Chlorideaverage · range 10 to 76 · Groundwater wells, highest of 2 sources · 2025 report, page 3 | 25 ppm | — | 250 ppm guideline | Within the guideline |
| Chlorinehighest running annual average · range 0.21 to 1.81 · Distribution system · 2025 report, page 3 | 0.97 ppm | None set | 4 ppm | Below the legal limit |
| Copper90th percentile of 32 homes tested, 0 over the action level · sampled 2024 · Customer taps · 2025 report, page 3 | 0.15 ppm | 0.3 ppm | 1.3 ppm (action level) | Below the health goal |
| Disinfection byproducts (HAA5)highest running annual average · range 14 to 41 · Distribution system · 2025 report, page 3 | 35 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)highest running annual average · range 13 to 45 · Distribution system · 2025 report, page 3 | 38 ppb | None set | 80 ppb | Below the legal limit |
| Fluorideaverage · range ND to 0.2 · Groundwater wells · 2025 report, page 3 | 0.1 ppm | 1 ppm | 2 ppm | Below the health goal |
| Lead90th percentile of 32 homes tested, 0 over the action level · sampled 2024 · Customer taps · 2025 report, page 3 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| Nitrate (as N)average · range 0.4 to 7.4 · Groundwater wells · 2025 report, page 3 | 3.4 ppm | 10 ppm | 10 ppm | Below the health goal |
| PFHxS (a PFAS)average · range ND to 7.5 · Groundwater wells · 2025 report, page 3 | Not detected | None set | 10 ppt from 2029 | Not detected |
| PFOA (a PFAS)average · range ND to 2.8 · Groundwater wells · 2025 report, page 3 | Not detected | 0.007 ppt | 4 ppt from 2029 | Not detected |
| Sulfateaverage · range 11 to 47 · Groundwater wells, highest of 2 sources · 2025 report, page 3 | 24 ppm | — | 250 ppm guideline | Within the guideline |
| Total dissolved solidsaverage · range 220 to 540 · Groundwater wells, highest of 2 sources · 2025 report, page 3 | 338 ppm | — | 500 ppm guideline | Within the guideline |
| Turbidity (cloudiness)highest measured · SSJID (DeGroot plant) · 2025 report, page 3 | 0.05 NTU | None set | 1 NTU | Below the legal limit |
| Hardnessaverage · range 4.15 to 18.6 · Groundwater wells · 2025 report, page 3 | 9.24 gpg (158 ppm) | — | — | Hard |
| Sodiumaverage · range 25 to 46 · Groundwater wells · 2025 report, page 3 | 34 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. 1 number we weren’t sure about is held back until a person checks.
EPA testing for PFAS and lithium
EPA’s own nationwide testing (UCMR 5) found these in City of Manteca’s water between Jan 2025 and Oct 2025. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- PFOA7 pptFound in 4 of 24 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
- PFHxS19 pptFound in 6 of 24 samples · highest resultNo federal limit in force for this one
- PFBS3.9 pptFound in 2 of 24 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.
Radium and uranium
Found: Gross alpha (radioactivity), Uranium
What removes it: Reverse osmosis.
PFAS ("forever chemicals")
Found: PFOA (EPA testing)
What removes it: Reverse osmosis.
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