We read 6 results from Lake Oswego Municipal Water’s 2025 water quality report. No results over a legal limit; 1 above a health goal or guideline.
Serves about 40,000 people · Water system ID OR4100457 · 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 |
|---|---|---|---|---|
| Bromateas reported · range 1 to 1 · listed as a violation in the report · printed as 0.0004 ppm · Treatment plant · 2025 report, page 2 | 0.4 ppb | 0.1 ppb | 10 ppb | Above the health goal4x the health goal |
| Chlorineaverage · range 0.1 to 1.34 · Distribution system · 2025 report, page 2 | 0.94 ppm | None set | 4 ppm | Below the legal limit |
| Copper90th percentile of homes tested, 0 over the action level · listed as a violation in the report · sampled 2023 · Customer taps · 2025 report, page 2 | Not detected | 0.3 ppm | 1.3 ppm (action level) | Not detected |
| Disinfection byproducts (HAA5)highest running annual average · range 1.2 to 7.4 · listed as a violation in the report · printed as 0.0042 ppm · Distribution system · 2025 report, page 2 | 4.2 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)highest running annual average · range 2.4 to 20 · listed as a violation in the report · printed as 0.0086 ppm · Distribution system · 2025 report, page 2 | 8.6 ppb | None set | 80 ppb | Below the legal limit |
| Lead90th percentile of homes tested, 0 over the action level · listed as a violation in the report · sampled 2023 · Customer taps · 2025 report, page 2 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
Utility results describe the whole system, measured where water enters the pipes, not your tap. Your home’s plumbing can add lead or copper.
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.
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