We read 15 results from Golden State Water Company - Simi Valley’s 2025 water quality report. No results over a legal limit; 4 above a health goal or guideline.
Serves about 45,128 people · Water system ID CA5610059 · 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 |
|---|---|---|---|---|
| Bromateaverage · range ND to 6.7 · Distribution system · 2025 report, page 9 | 4.1 ppb | 0.1 ppb | 10 ppb | Above the health goal41x the health goal |
| Copper90th percentile of 35 homes tested, 0 over the action level · sampled 2023 · Customer taps · 2025 report, page 9 | 0.48 ppm | 0.3 ppm | 1.3 ppm (action level) | Above the health goal1.6x the health goal |
| Gross alpha (radioactivity)average · range ND to 4.2 · Treated source water · 2025 report, page 8 | 1.4 pCi/L | 0 pCi/L | 15 pCi/L | Above the health goalThe health goal is zero |
| Uraniumaverage · range 1.79 to 11.9 · printed as 3.8 pCi/L · Treated source water · 2025 report, page 8 | 5.66 ppb | 0.6 ppb | 30 ppb | Above the health goal9.4x the health goal |
| Chloramineaverage · range 0.4 to 3.4 · Distribution system · 2025 report, page 9 | 1.8 ppm | None set | 4 ppm | Below the legal limit |
| Disinfection byproducts (HAA5)average · range ND to 5.5 · Distribution system · 2025 report, page 9 | 4.7 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)average · range 6.5 to 25 · Distribution system · 2025 report, page 9 | 16 ppb | None set | 80 ppb | Below the legal limit |
| Fluorideaverage · range 0.2 to 1.1 · Treated source water · 2025 report, page 8 | 0.7 ppm | 1 ppm | 2 ppm | Below the health goal |
| Lead90th percentile of 35 homes tested, 0 over the action level · sampled 2023 · Customer taps · 2025 report, page 9 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| Nitrate (as N)average · range ND to 4.8 · Treated source water · 2025 report, page 8 | 1.2 ppm | 10 ppm | 10 ppm | Below the health goal |
| Seleniumaverage · range ND to 19 · Treated source water · 2025 report, page 8 | 7.7 ppb | 30 ppb | 50 ppb | Below the health goal |
| Total dissolved solidsaverage · range 293 to 800 · Treated source water · 2025 report, page 8 | 500 ppm | — | 500 ppm guideline | Within the guideline |
| Hardnessaverage · range 8.01 to 19.3 · Treated source water · 2025 report, page 8 | 12.3 gpg (210 ppm) | — | — | Very hard |
| Lithiumaverage · range ND to 36 · Treated source water · 2025 report, page 8 | 17 ppb | None set | None | No health limit |
| Sodiumaverage · range 46 to 100 · Treated source water · 2025 report, page 8 | 78 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 Golden State Water Company - Simi Valley’s water between Jun 2024 and Mar 2025. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- Lithium35.5 ppbFound in 4 of 6 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), Uranium
What removes it: Reverse osmosis.
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