We read 20 results from Roslyn WD’s 2025 water quality report. No results over a legal limit; 6 above a health goal or guideline.
Serves about 17,000 people · Water system ID NY2902851 · Read the district’s 2025 report (opens in a new tab)
Open this district in the water lookupCompare with your own test results, see the district map and get matched filters.
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 |
|---|---|---|---|---|
| Chromium-6highest measured · range ND to 0.76 · 2025 report, page 4 | 0.76 ppb | 0.02 ppb | 10 ppb | Above the health goal38x the health goal |
| Gross alpha (radioactivity)highest measured · range 1.08 to 1.4 · 2025 report, page 4 | 1.4 pCi/L | 0 pCi/L | 15 pCi/L | Above the health goalThe health goal is zero |
| Perchloratehighest measured · range ND to 2.2 · 2025 report, page 4 | 2.2 ppb | 1 ppb | 6 ppb | Above the health goal2.2x the health goal |
| PFOA (a PFAS)highest measured · range ND to 7.1 · 2025 report, page 4 | 7.1 ppt | 0.007 ppt | 10 ppt (New York) now; 4 ppt from 2029 | Above the federal limit that takes effect in 20291.8x the 4 ppt federal limit that takes effect in 2029; below the 10 ppt New York limitNot a violation yet: EPA's 4 ppt limit is final, but water systems don't have to meet it until 2029. |
| PFOS (a PFAS)highest measured · range ND to 3.17 · 2025 report, page 4 | 3.17 ppt | 1 ppt | 10 ppt (New York) now; 4 ppt from 2029 | Above the health goal3.2x the health goal |
| Radium (combined 226 + 228)highest measured · range 0.09 to 1.45 · 2025 report, page 4 | 1.45 pCi/L | 0 pCi/L | 5 pCi/L | Above the health goalThe health goal is zero |
| Bariumhighest measured · range 0.0052 to 0.04 · 2025 report, page 4 | 0.04 ppm | 2 ppm | 2 ppm | Below the health goal |
| Chloridehighest measured · range 5.1 to 59.4 · 2025 report, page 4 | 59.4 ppm | — | 250 ppm guideline | Within the guideline |
| Copper90th percentile of homes tested · sampled 2023 · 2025 report, page 4 | 0.08 ppm | 0.3 ppm | 1.3 ppm (action level) | Below the health goal |
| Disinfection byproducts (TTHM)highest measured · range ND to 1 · 2025 report, page 4 | 1 ppb | None set | 80 ppb | Below the legal limit |
| Lead90th percentile of homes tested · sampled 2023 · 2025 report, page 4 | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| Nitrate (as N)highest measured · range 1.1 to 5.5 · 2025 report, page 4 | 5.5 ppm | 10 ppm | 10 ppm | Below the health goal |
| PFHxS (a PFAS)highest measured · range ND to 2.85 · 2025 report, page 4 | 2.85 ppt | None set | 10 ppt from 2029 | Below the legal limit |
| Sulfatehighest measured · range ND to 35.1 · 2025 report, page 4 | 35.1 ppm | — | 250 ppm guideline | Within the guideline |
| 1,4-Dioxanehighest measured · range ND to 0.55 · 2025 report, page 4 | 0.55 ppb | None set | None | No health limit |
| Calciumhighest measured · range 2.9 to 29.7 · 2025 report, page 4 | 29.7 ppm | None set | None | No health limit |
| Magnesiumhighest measured · range 1.4 to 16.8 · 2025 report, page 4 | 16.8 ppm | None set | None | No health limit |
| PFBA (a PFAS)highest measured · range ND to 2.64 · 2025 report, page 4 | 2.64 ppt | None set | None | No health limit |
| PFHxA (a PFAS)highest measured · range ND to 3.07 · 2025 report, page 4 | 3.07 ppt | None set | None | No health limit |
| Sodiumhighest measured · range 3.8 to 25.6 · 2025 report, page 4 | 25.6 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 Roslyn WD’s water between Oct 2024 and May 2025. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- PFOA5.6 pptFound in 2 of 16 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
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), Radium (combined 226 + 228)
What removes it: Reverse osmosis.
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)
What removes it: Reverse osmosis.
More districts: New York water quality · All states · Something look wrong? Tell us