We read 13 results from City of Colton’s 2024 water quality report. No results over a legal limit; 3 above a health goal or guideline.
Serves about 46,525 people · Water system ID CA3610014 · Read the district’s 2024 report (opens in a new tab)
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Results from the 2024 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 |
|---|---|---|---|---|
| Perchlorateaverage · range ND to 4.6 · listed as a violation in the report · Colton/Rialto wells · 2024 report, page 8 | 1.37 ppb | 1 ppb | 6 ppb | Above the health goal1.4x the health goal |
| PFOA (a PFAS)average · range 4.4 to 10 · listed as a violation in the report · Colton/Rialto wells · 2024 report, page 8 | 6.2 ppt | 0.007 ppt | 4 ppt from 2029 | Above the federal limit that takes effect in 20291.6x the 4 ppt federal limit that takes effect in 2029Not a violation yet: EPA's 4 ppt limit is final, but water systems don't have to meet it until 2029. |
| PFOS (a PFAS)average · range 6.3 to 18 · listed as a violation in the report · Colton/Rialto wells · 2024 report, page 8 | 13.3 ppt | 1 ppt | 4 ppt from 2029 | Above the federal limit that takes effect in 20293.3x the 4 ppt federal limit that takes effect in 2029Not a violation yet: EPA's 4 ppt limit is final, but water systems don't have to meet it until 2029. |
| Chlorineaverage · range 0.3 to 2.22 · listed as a violation in the report · Distribution system · 2024 report, page 8 | 1.12 ppm | None set | 4 ppm | Below the legal limit |
| Copper90th percentile of homes tested · printed as 130 ug/L · Customer taps · 2024 report, page 8 | 0.13 ppm | 0.3 ppm | 1.3 ppm (action level) | Below the health goal |
| Disinfection byproducts (TTHM)average · range 2.7 to 3 · listed as a violation in the report · Distribution system · 2024 report, page 8 | 2.85 ppb | None set | 80 ppb | Below the legal limit |
| Fluorideaverage · range 0.25 to 0.64 · listed as a violation in the report · Colton/Rialto wells · 2024 report, page 6 | 0.44 ppm | 1 ppm | 2 ppm | Below the health goal |
| Lead90th percentile of homes tested · Customer taps · 2024 report, page 8 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| Nitrate (as N)average · range ND to 7.3 · listed as a violation in the report · Colton/Rialto wells · 2024 report, page 6 | 4.35 ppm | 10 ppm | 10 ppm | Below the health goal |
| PFHxS (a PFAS)average · range 4.7 to 9.5 · listed as a violation in the report · Colton/Rialto wells · 2024 report, page 8 | 6.6 ppt | None set | 10 ppt from 2029 | Below the legal limit |
| Sulfateaverage · range 25 to 69 · listed as a violation in the report · Colton/Rialto wells · 2024 report, page 7 | 51.3 ppm | — | 250 ppm guideline | Within the guideline |
| Total dissolved solidsaverage · range 270 to 400 · listed as a violation in the report · Colton/Rialto wells · 2024 report, page 7 | 338 ppm | — | 500 ppm guideline | Within the guideline |
| Conductivityaverage · range 440 to 620 · listed as a violation in the report · Colton/Rialto wells · 2024 report, page 6 | 530 µS/cm | 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 City of Colton’s water between Jul 2023 and Feb 2025. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- PFOA5.9 pptFound in 2 of 15 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
- PFOS18 pptFound in 5 of 15 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
- PFHxS5.1 pptFound in 5 of 15 samples · highest resultNo federal limit in force for this one
- PFBS10 pptFound in 3 of 15 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.
Industrial chemicals and pesticides
Found: Perchlorate
What removes it: Carbon block or RO.
PFAS ("forever chemicals")
Found: PFOA (a PFAS), PFOS (a PFAS), PFOA (EPA testing), PFOS (EPA testing)
What removes it: Reverse osmosis.
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