Data & Methodology — Cuyahoga County

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

Contaminant Data — All Analytes

66524 total samples analyzed across 20 analytes. Data spans 1964 to 2021.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. OH Avg
Manganese 10 1964–1974 90%
360% of limit ~ typical
Lead 4 1970–1974 75%
120% of limit ↑ 300% above
Iron 73 1964–1997 99%
168% of limit ↓ 69% below
Chloride 63 1964–2021 98%
40% of limit ~ typical
Arsenic 10 1970–1974 90%
50% of limit ~ typical
Sulfate 48 1964–2019 100%
28% of limit ↓ 51% below
Fluoride 30 1964–1974 97%
38% of limit ↑ 122% above
Nitrite 51 1999–2017 98%
6% of limit ↓ 40% below
Nitrate 5 2008–2015 100%
4% of limit ↑ 86% above
HFPO-DA (GenX) municipal 38 2023–2025 0%
0% of limit —
PFHxS municipal 38 2023–2025 0%
0% of limit —
PFNA municipal 42 2008–2022 69%
0% of limit —
PFOS municipal 41 2020–2022 37%
0% of limit —
PFOA municipal 42 2008–2022 83%
0% of limit —
PFBS municipal 38 2023–2025 0%
— —
pH 26 1964–2010 85% — — ~ typical
Hardness 36 1999–2018 100% — — ↓ 36% below
Sodium 82 1974–2018 100% — — ~ typical
E. coli 1 1997 0%
— —
Fecal Coliform 1 1989 0%
— —

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.

Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 73 samples
  • Chloride 63 samples
  • Sulfate 48 samples
  • Fluoride 30 samples
  • Nitrite 51 samples
  • PFNA 42 samples
  • PFOS 41 samples
  • PFOA 42 samples
  • pH 26 samples
  • Hardness 36 samples
  • Sodium 82 samples

Limited data (<15 samples) — interpret with caution

  • Manganese 10 samples
  • Lead 4 samples
  • Arsenic 10 samples
  • Nitrate 5 samples
  • E. coli 1 sample
  • Fecal Coliform 1 sample

Public vs. Private Water in Cuyahoga County

11 Active public water systems
1,411,268 Residents on public water

Public water systems in Cuyahoga 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 Cuyahoga 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 Cuyahoga County Prevalence OH Average Source Year
Arsenic Cancer prevalence 7.2% 6.8% 2020
Arsenic Kidney disease rate 3.5% 3.1% 2020
Lead Heart disease rate 6.3% 7.6% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Cuyahoga 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: 2026-05-28

Full methodology →