Full contaminant data, sample history, and sourcing for New York County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
41 well testing events on record, covering
18 analytes.
Data spans 1970 to 2025.
Contaminant
Samples
Years
Detection Rate
Distribution LowModHigh
vs. Limit
vs. NY Avg
Manganese
33
2006–2011
100%
1504% of limit
↑ 386% above
Iron
33
2006–2011
100%
530% of limit
↑ 174% above
Chloride
34
1973–2011
100%
122% of limit
↑ 313% above
Sulfate
34
1973–2011
100%
29% of limit
↑ 115% above
Nitrate
34
1973–2011
50%
30% of limit
↑ 155% above
Arsenic
34
1973–2011
82%
5% of limit
↓ 73% below
Fluoride
34
1973–2011
97%
5% of limit
~ typical
HFPO-DA (GenX)
municipal
16
2023–2025
0%
—
—
Lead
33
2006–2011
88%
3% of limit
↓ 25% below
Nitrite
33
2006–2011
61%
1% of limit
~ typical
PFHxS
municipal
16
2023–2025
0%
—
—
PFNA
municipal
16
2023–2025
0%
—
—
PFOA
municipal
16
2023–2025
0%
—
—
PFOS
municipal
16
2023–2025
0%
—
—
Hardness
1
1973
100%
—
↑ 67% above
PFBS
municipal
16
2023–2025
0%
—
—
pH
34
1973–2011
100%
—
~ typical
Sodium
34
1973–2011
100%
—
↑ 184% above
Distribution shows the share of samples in each concentration band relative to the EPA Maximum Contaminant Level (MCL): Low = below half the MCL, Moderate = between half and the MCL, High = above the MCL. Analytes without an MCL (e.g. sodium, pH) show — in the limit columns. State average is based on county median values across NY.
Compare your result with New York County
Of the 34 arsenic tests on record for New York County (1973–2011),
18% found none, and half were below 0.44 µg/L.
Of the 34 chloride tests on record for New York County (1973–2011),
0% found none, and half were below 304 mg/L.
Of the 34 fluoride tests on record for New York County (1973–2011),
3% found none, and half were below 205 µg/L.
Of the 33 iron tests on record for New York County (2006–2011),
0% found none, and half were below 1.59 mg/L.
Of the 33 lead tests on record for New York County (2006–2011),
12% found none, and half were below 0.39 µg/L.
Of the 33 manganese tests on record for New York County (2006–2011),
0% found none, and half were below 752 µg/L.
Of the 34 nitrate tests on record for New York County (1973–2011),
50% found none, and half were below 157 µg/L.
Of the 34 sulfate tests on record for New York County (1973–2011),
0% found none, and half were below 73.1 mg/L.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Manganese 33 samples
Iron 33 samples
Chloride 34 samples
Sulfate 34 samples
Nitrate 34 samples
Arsenic 34 samples
Fluoride 34 samples
Lead 33 samples
Nitrite 33 samples
pH 34 samples
Sodium 34 samples
Limited data (<15 samples) — interpret with caution
Hardness 1 sample
No private-well PFAS data for New York County
We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in New York County.
PFAS testing for private wells requires a dedicated lab panel (~$300–$500). If you are near a military base, airport, or industrial site, consider testing proactively. Learn more about PFAS →
CDC Health Outcome Correlations
Where contaminants detected in New York County have established associations with specific health outcomes, we cross-reference CDC PLACES county-level prevalence data. This is a contextual signal, not a causal claim.
This report aggregates data from the following public databases:
Water Quality Portal (WQP) — groundwater sample results for New York County from EPA, USGS, and state agencies. Browse WQP data →
EPA Safe Drinking Water Information System (SDWIS) — public water system inventory used to estimate the share of residents on private wells. Browse SDWIS →
Census ACS 5-Year Estimates — well and cistern household counts (variable DP04_0074E) used to calculate the private-well percentage for New York County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying New York County, which informs which contaminants are geologically likely. USGS Aquifer Atlas →
EPA UCMR 5 (2023–2025) — PFAS occurrence data from public water systems, used as a proxy indicator for aquifer PFAS exposure. Rows marked "municipal" in the table above come from this source. About UCMR 5 →
EPA Toxics Release Inventory (TRI) — industrial facility chemical releases near New York County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near New York County, used in contamination risk scoring. Superfund site search →
CDC PLACES — county-level health outcome prevalence (kidney disease, cancer, heart disease) correlated with detected contaminants. About CDC PLACES →
Methodology
Raw records are downloaded from the Water Quality Portal and normalized to µg/L (ppb). Records are deduplicated by sample ID and date, and certified outliers are excluded. Analyte names are mapped to EPA canonical forms. Detection rates, distribution bands, and MCL comparisons are computed from the normalized dataset.
Distribution bands use the EPA Maximum Contaminant Level as the threshold: concentrations below 50% of the MCL are classed as Low, between 50% and 100% as Moderate, and above 100% as High. For analytes without an MCL (sodium, hardness, pH), distribution is not computed.
State comparison uses the median of county median values across all counties in NY with at least one sample for that analyte.