We read 13 results from California Water Service Co. - Dominguez’s 2025 water quality report. No results over a legal limit; 2 above a health goal or guideline.
Serves about 143,996 people · Water system ID CA1910033 · Read the district’s 2025 report (opens in a new tab)
Open this district in the water lookupCompare with your own test results, see the district map and get matched filters.
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 |
|---|---|---|---|---|
| Copper90th percentile of 50 homes tested, 0 over the action level · sampled 2023 · Customer taps (50 sites) · 2025 report, page 13 | 0.31 ppm | 0.3 ppm | 1.3 ppm (action level) | Above the health goal1x the health goal |
| Gross alpha (radioactivity)highest measured · range ND to 3 · sampled 2024 · Groundwater wells · 2025 report, page 13 | 3 pCi/L | 0 pCi/L | 15 pCi/L | Above the health goalThe health goal is zero |
| Chloramineaverage · range 0.2 to 3.2 · Distribution system · 2025 report, page 13 | 1.9 ppm | None set | 4 ppm | Below the legal limit |
| Disinfection byproducts (HAA5)highest running annual average · range ND to 21 · Distribution system · 2025 report, page 13 | 18 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)highest running annual average · range 2.5 to 63 · Distribution system · 2025 report, page 13 | 47 ppb | None set | 80 ppb | Below the legal limit |
| Fluorideaverage · range 0.18 to 0.73 · Groundwater wells · 2025 report, page 13 | 0.54 ppm | 1 ppm | 2 ppm | Below the health goal |
| Lead90th percentile of 50 homes tested, 0 over the action level · sampled 2023 · Customer taps (50 sites) · 2025 report, page 13 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| Manganesehighest measured · range ND to 0.04 · printed as 35 ppb · Groundwater wells · 2025 report, page 14 | 0.04 ppm | — | 0.05 ppm guideline | Within the guideline |
| PFHxS (a PFAS)highest measured · range ND to 3.6 · Groundwater wells · 2025 report, page 14 | 3.6 ppt | None set | 10 ppt from 2029 | Below the legal limit |
| Seleniumhighest measured · range ND to 5.7 · Groundwater wells · 2025 report, page 13 | 5.7 ppb | 30 ppb | 50 ppb | Below the health goal |
| Total dissolved solidsaverage · range ND to 580 · Groundwater wells · 2025 report, page 14 | 278 ppm | — | 500 ppm guideline | Within the guideline |
| Hardnessaverage · range 2.81 to 17.5 · Groundwater wells · 2025 report, page 15 | 7.37 gpg (126 ppm) | — | — | Hard |
| Sodiumaverage · range 46 to 88 · Groundwater wells · 2025 report, page 15 | 59 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 California Water Service Co. - Dominguez’s water between Jan 2024 and Oct 2025. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- PFHxS3.5 pptFound in 2 of 19 samples · highest resultNo federal limit in force for this one
- Lithium64.7 ppbFound in 6 of 19 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.
Radium and uranium
Found: Gross alpha (radioactivity)
What removes it: Reverse osmosis.
More districts: California water quality · All states · Something look wrong? Tell us