We read 13 results from Natick Water and Sewer Division’s 2025 water quality report. No results over a legal limit; 1 above a health goal or guideline.
Serves about 37,006 people · Water system ID MA3198000 · 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 |
|---|---|---|---|---|
| Copper90th percentile of 30 homes tested, 0 over the action level · listed as a violation in the report · Customer taps · 2025 report, page 5 | 0.36 ppm | 0.3 ppm | 1.3 ppm (action level) | Above the health goal1.2x the health goal |
| Bariumhighest measured · listed as a violation in the report · Treated water · 2025 report, page 5 | 0.03 ppm | 2 ppm | 2 ppm | Below the health goal |
| Chlorinehighest running annual average · range 0.17 to 1 · listed as a violation in the report · Distribution system · 2025 report, page 5 | 0.54 ppm | None set | 4 ppm | Below the legal limit |
| Disinfection byproducts (HAA5)highest running annual average · range 1.7 to 7.7 · listed as a violation in the report · Distribution system · 2025 report, page 5 | 5.5 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)highest running annual average · range 9.3 to 30 · listed as a violation in the report · Distribution system · 2025 report, page 5 | 24 ppb | None set | 80 ppb | Below the legal limit |
| Fluoridehighest measured · range 0.3 to 0.8 · listed as a violation in the report · Treated water · 2025 report, page 5 | 0.8 ppm | 1 ppm | 4 ppm | Below the health goal |
| Lead90th percentile of 30 homes tested, 0 over the action level · listed as a violation in the report · Customer taps · 2025 report, page 5 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| Nitrate (as N)highest measured · range 0.84 to 1.2 · listed as a violation in the report · Treated water · 2025 report, page 5 | 1.2 ppm | 10 ppm | 10 ppm | Below the health goal |
| Perchloratehighest measured · range 0.08 to 0.25 · listed as a violation in the report · sampled 2023 · Treated water · 2025 report, page 5 | 0.17 ppb | 1 ppb | 6 ppb | Below the health goal |
| Hardnessaverage · range 4.76 to 7.84 · Treated water · 2025 report, page 5 | 6.32 gpg (108 ppm) | — | — | Moderately hard |
| PFAS (total of measured)highest running annual average · range ND to 16.7 · listed as a violation in the report · Treated water · 2025 report, page 5 | 10 ppt | None set | None | No health limit |
| PFBS (a PFAS)average · range ND to 3.6 · Treated water · 2025 report, page 5 | 1.8 ppt | None set | None | No health limit |
| Sodiumsingle sample · Treated water · 2025 report, page 5 | 44.5 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 Natick Water and Sewer Division’s water between Dec 2024 and Jun 2025. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- PFOA14.3 pptFound in 4 of 8 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
- PFOS37.3 pptFound in 4 of 8 samples · highest resultHighest sample is above the 20 ppt Massachusetts limit (for the sum of 6 PFAS). Compliance is judged on averages, not one sample.
- PFHxS11.2 pptFound in 2 of 8 samples · highest resultNo federal limit in force for this one
- PFBS6.5 pptFound in 4 of 8 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.
Copper
Found: Copper
What removes it: Reverse osmosis.
PFAS ("forever chemicals")
Found: PFOA (EPA testing), PFOS (EPA testing)
What removes it: Reverse osmosis.
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