Data & Methodology — Miami County

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

Contaminant Data — All Analytes

222 well testing events on record, covering 22 analytes. Data spans 1965 to 2024.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. OH Avg
Iron 204 1974–2020 96%
500% of limit ~ typical
Manganese 202 1974–2020 94%
94% of limit ↓ 47% below
Arsenic 138 1974–2020 85%
10% of limit ↓ 37% below
Lead 141 1974–2020 54%
0% of limit ↓ 100% below
Chloride 203 1974–2020 100%
12% of limit ↓ 21% below
Fluoride 141 1974–2020 100%
20% of limit ↑ 95% above
HFPO-DA (GenX) municipal 12 2023–2025 0%
— —
Nitrate 116 1974–2020 45%
0% of limit ↓ 96% below
Nitrite 118 1974–2020 28%
1% of limit ↑ 57% above
PFHxS municipal 12 2023–2025 0%
— —
PFNA municipal 13 2008–2025 0%
— —
PFOA municipal 13 2008–2025 0%
— —
PFOS municipal 12 2023–2025 0%
— —
Radon 6 1999–2000 100%
8% of limit ↓ 65% below
Sulfate 142 1974–2020 100%
24% of limit ↓ 44% below
Uranium 22 1999–2020 91%
6% of limit ↑ 143% above
E. coli 2 2019 0%
— —
Hardness 202 1974–2020 100%
— ~ typical
PFBS municipal 12 2023–2025 0%
— —
pH 201 1974–2020 100%
— ~ typical
Sodium 163 1976–2020 100%
— ↓ 39% below
Total Coliform 2 2019 50%
— ~ typical

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 OH.

Compare your result with Miami County

Of the 138 arsenic tests on record for Miami County (1974–2020), 15% found none, and half were below 0.295 µg/L.

Of the 203 chloride tests on record for Miami County (1974–2020), 0% found none, and half were below 30 mg/L.

Of the 141 fluoride tests on record for Miami County (1974–2020), 0% found none, and half were below 800 µg/L.

Of the 204 iron tests on record for Miami County (1974–2020), 4% found none, and half were below 1.48 mg/L.

Of the 141 lead tests on record for Miami County (1974–2020), 46% found none.

Of the 202 manganese tests on record for Miami County (1974–2020), 6% found none, and half were below 46.2 µg/L.

Of the 116 nitrate tests on record for Miami County (1974–2020), 55% found none.

Of the 142 sulfate tests on record for Miami County (1974–2020), 0% found none, and half were below 61.2 mg/L.

Of the 22 uranium tests on record for Miami County (1999–2020), 9% found none, and half were below 1.62 µg/L.

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)

  • Iron 204 samples
  • Manganese 202 samples
  • Arsenic 138 samples
  • Lead 141 samples
  • Chloride 203 samples
  • Fluoride 141 samples
  • Nitrate 116 samples
  • Nitrite 118 samples
  • Sulfate 142 samples
  • Uranium 22 samples
  • Hardness 202 samples
  • pH 201 samples
  • Sodium 163 samples

Limited data (<15 samples) — interpret with caution

  • PFNA 13 samples
  • PFOA 13 samples
  • Radon 6 samples
  • E. coli 2 samples
  • Total Coliform 2 samples

Public vs. Private Water in Miami County

57 Active public water systems
94,299 Residents on public water
19% Households on private wells

Public water systems in Miami 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 Miami 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 Miami County Prevalence OH Average Source Year
Arsenic Cancer prevalence 7.7% 6.8% 2020
Arsenic Kidney disease rate 3.1% 3.1% 2020
Lead Heart disease rate 7.9% 7.6% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Miami 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 OH with at least one sample for that analyte.

Last updated: 2026-08-04

Full methodology →