We read 17 results from Rainbow Municipal WD’s 2025 water quality report. No results over a legal limit; 2 above a health goal or guideline.
Serves about 23,536 people · Water system ID CA3710016 · 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 |
|---|---|---|---|---|
| Total dissolved solidsaverage · range 501 to 513 · MWD Skinner Water Treatment Plant (supplier) · 2025 report, page 11 | 507 ppm | — | 500 ppm guideline | Above the guideline1x the guideline (taste, odor or stains; not a health limit) |
| Uraniumaverage · range ND to 4.47 · printed as 2 pCi/L · MWD Skinner Water Treatment Plant (supplier) · 2025 report, page 11 | 2.98 ppb | 0.6 ppb | 30 ppb | Above the health goal5x the health goal |
| Aluminumaverage · range ND to 0.12 · printed as 57 ppb · MWD Skinner Water Treatment Plant (supplier) · 2025 report, page 10 | 0.06 ppm | — | 0.2 ppm guideline | Within the guideline |
| Chloramineaverage · range 1.48 to 2.44 · Distribution system · 2025 report, page 11 | 2 ppm | None set | 4 ppm | Below the legal limit |
| Chlorideaverage · range 87 to 91 · MWD Skinner Water Treatment Plant (supplier) · 2025 report, page 11 | 89 ppm | — | 250 ppm guideline | Within the guideline |
| Coloraverage · range 1 to 2 · MWD Skinner Water Treatment Plant (supplier) · 2025 report, page 11 | 2 CU | — | 15 CU guideline | Within the guideline |
| Copper90th percentile of 30 homes tested, 0 over the action level · sampled 2024 · Customer taps · 2025 report, page 10 | 0.24 ppm | 0.3 ppm | 1.3 ppm (action level) | Below the health goal |
| Disinfection byproducts (HAA5)average · range 3 to 18 · Distribution system · 2025 report, page 11 | 10 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)average · range 17 to 58 · Distribution system · 2025 report, page 11 | 33 ppb | None set | 80 ppb | Below the legal limit |
| Fluorideaverage · range 0.6 to 0.8 · MWD Skinner Water Treatment Plant (supplier) · 2025 report, page 10 | 0.7 ppm | 1 ppm | 2 ppm | Below the health goal |
| Sulfateaverage · range 164 to 171 · MWD Skinner Water Treatment Plant (supplier) · 2025 report, page 11 | 168 ppm | — | 250 ppm guideline | Within the guideline |
| Turbidity (cloudiness)highest measured · MWD Skinner Water Treatment Plant (supplier) · 2025 report, page 10 | 0.07 NTU | None set | 1 NTU | Below the legal limit |
| Boronaverage · printed as 130 ppb · MWD Skinner Water Treatment Plant (supplier) · 2025 report, page 11 | 0.13 ppm | None set | None | No health limit |
| Conductivityaverage · range 824 to 847 · MWD Skinner Water Treatment Plant (supplier) · 2025 report, page 11 | 836 µS/cm | None set | None | No health limit |
| Hardnessaverage · range 13.3 to 13.6 · MWD Skinner Water Treatment Plant (supplier) · 2025 report, page 11 | 13.5 gpg (230 ppm) | — | — | Very hard |
| Lithiumaverage · range 26 to 30 · Rainbow MWD · 2025 report, page 11 | 28 ppb | None set | None | No health limit |
| Sodiumaverage · range 83 to 87 · MWD Skinner Water Treatment Plant (supplier) · 2025 report, page 11 | 85 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 Rainbow Municipal WD’s water between May 2024 and Feb 2025. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- Lithium44 ppbFound in 4 of 4 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.
Salty taste / high TDS
Found: Total dissolved solids
What removes it: Reverse osmosis.
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