Data & Methodology — Carroll County

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

Contaminant Data — All Analytes

42 well testing events on record, covering 20 analytes. Data spans 1963 to 2024.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. VA Avg
Manganese 11 1963–2014 82%
47% of limit ↓ 63% below
Radon 9 1997–2014 100%
14% of limit ↓ 83% below
Iron 14 1963–2014 57%
9% of limit ↓ 89% below
Uranium 9 1997–2014 11%
3% of limit ↑ 366% above
Sulfate 14 1963–2014 93%
1% of limit ↓ 89% below
PFOA municipal 6 2024 0%
— —
PFHxS municipal 6 2024 0%
— —
Nitrite 12 1979–2014 8%
0% of limit ↓ 72% below
Chloride 14 1963–2014 100%
1% of limit ↓ 92% below
Arsenic 10 1979–2014 10%
30% of limit ↑ 297% above
Fluoride 13 1963–2014 23%
2% of limit ↓ 53% below
HFPO-DA (GenX) municipal 6 2024 0%
— —
Lead 11 1971–2014 18%
4% of limit ↑ 48% above
Nitrate 13 1963–2014 92%
3% of limit ↓ 49% below
PFNA municipal 6 2024 0%
— —
PFOS municipal 6 2024 0%
— —
Sodium 14 1963–2014 100%
— ↓ 83% below
pH 14 1963–2014 100%
— ~ typical
PFBS municipal 6 2024 0%
— —
Hardness 14 1963–2014 100%
— ↓ 66% below

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.

Data Coverage & Gaps

Limited data (<15 samples) — interpret with caution

  • Manganese 11 samples
  • Radon 9 samples
  • Iron 14 samples
  • Uranium 9 samples
  • Sulfate 14 samples
  • Nitrite 12 samples
  • Chloride 14 samples
  • Arsenic 10 samples
  • Fluoride 13 samples
  • Lead 11 samples
  • Nitrate 13 samples
  • Sodium 14 samples
  • pH 14 samples
  • Hardness 14 samples

No private-well PFAS data for Carroll County

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

30 Active public water systems
15,468 Residents on public water

Public water systems in Carroll 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 Carroll 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 Carroll County Prevalence VA Average Source Year
Radon Cancer prevalence 6.2% 6.7% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Carroll 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: 2026-07-15

Full methodology →