We read 12 results from Valley of the Moon Water District’s 2025 water quality report. No results over a legal limit or above a health goal.
Serves about 23,107 people · Water system ID CA4910013 · 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 |
|---|---|---|---|---|
| Chlorideaverage · range 4.3 to 4.9 · Sonoma County Water Agency (supplier) · 2025 report, page 5 | 4.62 ppm | — | 250 ppm guideline | Within the guideline |
| Copper90th percentile of 30 homes tested, 0 over the action level · sampled 2023 · Customer taps · 2025 report, page 5 | 0.19 ppm | 0.3 ppm | 1.3 ppm (action level) | Below the health goal |
| Lead90th percentile of 30 homes tested, 0 over the action level · sampled 2023 · Customer taps · 2025 report, page 5 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| pHaverage · range 7.3 to 7.56 · Sonoma County Water Agency (supplier) · 2025 report, page 6 | 7.43 | — | — | Normal range |
| Sulfateaverage · range 11 to 14 · Sonoma County Water Agency (supplier) · 2025 report, page 5 | 11.8 ppm | — | 250 ppm guideline | Within the guideline |
| Total dissolved solidsaverage · range 120 to 270 · Sonoma County Water Agency (supplier) · 2025 report, page 5 | 157 ppm | — | 500 ppm guideline | Within the guideline |
| Turbidity (cloudiness)average · range 0.03 to 0.03 · Sonoma County Water Agency (supplier) · 2025 report, page 5 | 0.03 NTU | None set | 1 NTU | Below the legal limit |
| Calciumaverage · range 20 to 24 · Sonoma County Water Agency (supplier) · 2025 report, page 6 | 21.2 ppm | None set | None | No health limit |
| Conductivityaverage · range 220 to 260 · Sonoma County Water Agency (supplier) · 2025 report, page 5 | 228 µS/cm | None set | None | No health limit |
| Hardnessaverage · range 6.2 to 7.31 · Sonoma County Water Agency (supplier) · 2025 report, page 6 | 6.42 gpg (110 ppm) | — | — | Moderately hard |
| Magnesiumaverage · range 13 to 16 · Sonoma County Water Agency (supplier) · 2025 report, page 6 | 13.7 ppm | None set | None | No health limit |
| Sodiumaverage · range 8 to 8.8 · Sonoma County Water Agency (supplier) · 2025 report, page 6 | 8.43 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 Valley of the Moon Water District’s water between Oct 2024 and Apr 2025. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- PFOA5.2 pptFound in 2 of 14 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
- PFOS5.4 pptFound in 1 of 14 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
- PFHxS4.2 pptFound in 2 of 14 samples · highest resultNo federal limit in force for this one
- PFBS4.2 pptFound in 3 of 14 samples · highest resultNo federal limit in force for this one
- Lithium36 ppbFound in 13 of 13 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.
PFAS ("forever chemicals")
Found: PFOA (EPA testing), PFOS (EPA testing)
What removes it: Reverse osmosis.
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