Data & Methodology — Northampton County

Full contaminant data, sample history, and sourcing for Northampton County. For readers who want to go beyond the summary.

Contaminant Data — All Analytes

776 well testing events on record, covering 14 analytes. Data spans 1945 to 2025.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. VA Avg
Manganese 113 1987–2023 78%
50% of limit ↓ 60% below
Nitrate 135 1954–2025 91%
45% of limit ↑ 1144% above
Iron 131 1954–2023 70%
12% of limit ↓ 90% below
Chloride 172 1945–2025 100%
12% of limit ↑ 246% above
Sulfate 149 1945–2025 93%
20% of limit ↑ 197% above
Lead 65 1987–2023 14%
1% of limit ↓ 39% below
Uranium 28 1998–2023 14%
0% of limit ↓ 95% below
Radon 6 1988–2012 100%
38% of limit ↑ 180% above
Fluoride 148 1954–2025 53%
5% of limit ~ typical
Arsenic 55 1988–2023 24%
2% of limit ↓ 27% below
Nitrite 119 1975–2025 50%
1% of limit ~ typical
pH 253 1954–2023 100%
— ~ typical
Sodium 148 1954–2025 100%
— ~ typical
Hardness 149 1945–2025 100%
— ↑ 39% 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 VA.

Compare your result with Northampton County

Of the 55 arsenic tests on record for Northampton County (1988–2023), 76% found none.

Of the 172 chloride tests on record for Northampton County (1945–2025), 0% found none, and half were below 30.9 mg/L.

Of the 148 fluoride tests on record for Northampton County (1954–2025), 47% found none, and half were below 15 µg/L.

Of the 131 iron tests on record for Northampton County (1954–2023), 30% found none, and half were below 16 µg/L.

Of the 65 lead tests on record for Northampton County (1987–2023), 86% found none.

Of the 113 manganese tests on record for Northampton County (1987–2023), 22% found none, and half were below 19 µg/L.

Of the 135 nitrate tests on record for Northampton County (1954–2025), 9% found none, and half were below 2.6 mg/L.

Of the 149 sulfate tests on record for Northampton County (1945–2025), 7% found none, and half were below 43 mg/L.

Of the 28 uranium tests on record for Northampton County (1998–2023), 86% found none.

Have a number from your lab? Enter it to see where it falls. Nothing is sent anywhere.

Want the full picture for your well? Check all your results.

Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Manganese 113 samples
  • Nitrate 135 samples
  • Iron 131 samples
  • Chloride 172 samples
  • Sulfate 149 samples
  • Lead 65 samples
  • Uranium 28 samples
  • Fluoride 148 samples
  • Arsenic 55 samples
  • Nitrite 119 samples
  • pH 253 samples
  • Sodium 148 samples
  • Hardness 149 samples

Limited data (<15 samples) — interpret with caution

  • Radon 6 samples

No private-well PFAS data for Northampton County

We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Northampton 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 →

Public vs. Private Water in Northampton County

52 Active public water systems
16,015 Residents on public water
47% Households on private wells

Public water systems in Northampton County are regulated by the EPA and must test and report contaminant levels. Private well owners are responsible for their own testing — there is no routine monitoring of private wells by any government agency.

CDC Health Outcome Correlations

Where contaminants detected in Northampton 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.

Contaminant Associated Condition Northampton County Prevalence VA Average Source Year
Lead Heart disease rate 9.8% 6.7% 2020
Nitrate Cancer prevalence 5.8% 6.7% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Northampton County CDC PLACES data →

Data Sources

This report aggregates data from the following public databases:

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 VA with at least one sample for that analyte.

Last updated: 2026-08-04

Full methodology →