We read 12 results from Caldwell City of’s 2025 water quality report. No results over a legal limit; 3 above a health goal or guideline.
Serves about 74,000 people · Water system ID ID3140013 · 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 |
|---|---|---|---|---|
| Arsenichighest measured · range 3.9 to 9.24 · listed as a violation in the report · Wells · 2025 report, page 5 | 9.24 ppb | 0.004 ppb | 10 ppb | Above the health goal2,310x the health goal |
| Gross alpha (radioactivity)highest measured · range ND to 11 · listed as a violation in the report · Wells · 2025 report, page 5 | 11 pCi/L | 0 pCi/L | 15 pCi/L | Above the health goalThe health goal is zero |
| Uraniumhighest measured · range ND to 20 · listed as a violation in the report · Wells · 2025 report, page 5 | 20 ppb | 0.6 ppb | 30 ppb | Above the health goal33x the health goal |
| Bariumhighest measured · range 0.02 to 0.07 · listed as a violation in the report · Wells · 2025 report, page 5 | 0.07 ppm | 2 ppm | 2 ppm | Below the health goal |
| Chlorinehighest measured · range 0.17 to 0.62 · listed as a violation in the report · Distribution system · 2025 report, page 5 | 0.62 ppm | None set | 4 ppm | Below the legal limit |
| Chromium (total)highest measured · range ND to 3 · listed as a violation in the report · Wells · 2025 report, page 5 | 3 ppb | None set | 100 ppb | Below the legal limit |
| Copper90th percentile of 31 homes tested, 0 over the action level · listed as a violation in the report · sampled 2023 · Customer taps · 2025 report, page 5 | 0.08 ppm | 0.3 ppm | 1.3 ppm (action level) | Below the health goal |
| Disinfection byproducts (TTHM)highest measured · range ND to 0.57 · listed as a violation in the report · Distribution system · 2025 report, page 5 | 0.57 ppb | None set | 80 ppb | Below the legal limit |
| Fluoridehighest measured · range 0.27 to 0.46 · listed as a violation in the report · Wells · 2025 report, page 5 | 0.46 ppm | 1 ppm | 4 ppm | Below the health goal |
| Lead90th percentile of 31 homes tested, 0 over the action level · listed as a violation in the report · sampled 2023 · Customer taps · 2025 report, page 5 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| Nitrate (as N)highest measured · range ND to 2.2 · listed as a violation in the report · Wells · 2025 report, page 5 | 2.2 ppm | 10 ppm | 10 ppm | Below the health goal |
| Lithiumaverage · range 9.7 to 17 · sampled 2023 · Wells (UCMR5) · 2025 report, page 5 | 12.7 ppb | 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 Caldwell City of’s water between Apr 2023 and Aug 2025. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- Lithium16 ppbFound in 11 of 17 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.
Radium and uranium
Found: Gross alpha (radioactivity), Uranium
What removes it: Reverse osmosis.
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