Hamilton County Water Quality: 3 Cities Ranked by the Records
Hamilton County, Ohio: 3 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.
Highest result for each contaminant
One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.
Perfluorooctanesulfonic acid (PFOS)Detected in 1 system of 3 tested4.0 ng/L federal MCL (2024) · US EPAHighest6.1 ng/L
- CINCINNATI PUBLIC WATER SYSTEM6.1 ng/LSample date: 2023-05-10 to 2024-02-05
- HARRISON CITY PWSNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-06-06 to 2024-12-19
- READING CITY PWSNot detected · below 4.0 ng/L lab reporting limitSample date: 2025-01-21 to 2025-10-15
Water hardnessDetected in 1 systemAesthetic, no federal health limit · USGSHighest7.8 gpg
- CINCINNATI PUBLIC WATER SYSTEM7.8 gpgReporting year: 2025
Lead (90th percentile)Detected in 2 systems of 3 tested15 µg/L federal action level · US EPAHighest2.05 µg/L
- CINCINNATI PUBLIC WATER SYSTEM2.05 µg/LMonitoring period: 2026–2026 (still open)
- READING CITY PWS1.9 µg/LMonitoring period: 2025–2025
- HARRISON CITY PWSNot detectedMonitoring period: 2026–2026 (still open)
Perfluorobutanesulfonic acid (PFBS)Detected in 1 system of 3 tested2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest4.1 ng/L
- CINCINNATI PUBLIC WATER SYSTEM4.1 ng/LSample date: 2023-05-10 to 2024-02-05
- HARRISON CITY PWSNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-06-06 to 2024-12-19
- READING CITY PWSNot detected · below 3.0 ng/L lab reporting limitSample date: 2025-01-21 to 2025-10-15
Perfluorobutanoic acid (PFBA)Detected in 1 system of 3 testedNo federal or state limit; shown for transparencyHighest5.2 ng/L
- CINCINNATI PUBLIC WATER SYSTEM5.2 ng/LSample date: 2023-05-10 to 2024-02-05
- HARRISON CITY PWSNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-06-06 to 2024-12-19
- READING CITY PWSNot detected · below 5.0 ng/L lab reporting limitSample date: 2025-01-21 to 2025-10-15
Perfluoropentanoic acid (PFPeA)Detected in 1 system of 3 testedNo federal or state limit; shown for transparencyHighest4.9 ng/L
- READING CITY PWS4.9 ng/LSample date: 2025-01-21 to 2025-10-15
- CINCINNATI PUBLIC WATER SYSTEMNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-10 to 2024-02-05
- HARRISON CITY PWSNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-06-06 to 2024-12-19
26 substances tested, none detected in any systemShow
Tested in these 3 systems: CINCINNATI PUBLIC WATER SYSTEM, HARRISON CITY PWS, READING CITY PWS
- 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
- 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
- 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
- 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
- 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
- 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
- Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
- Lithium
- N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
- N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
- Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
- Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
- Perfluoro-3-methoxypropanoic acid (PFMPA)
- Perfluoro-4-methoxybutanoic acid (PFMBA)
- Perfluorodecanoic acid (PFDA)
- Perfluorododecanoic acid (PFDoA)
- Perfluoroheptanesulfonic acid (PFHpS)
- Perfluoroheptanoic acid (PFHpA)
- Perfluorohexanesulfonic acid (PFHxS)
- Perfluorohexanoic acid (PFHxA)
- Perfluorononanoic acid (PFNA)
- Perfluorooctanoic acid (PFOA)
- Perfluoropentanesulfonic acid (PFPeS)
- Perfluorotetradecanoic acid (PFTA)
- Perfluorotridecanoic acid (PFTrDA)
- Perfluoroundecanoic acid (PFUnA)
Cities ranked by the records
Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.
0of 3 cities above the 15 µg/L action level
Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.
Lead in Ohio1city reports hardness · Cincinnati, 7.8 gpg
Hard on the USGS scale. An aesthetic measure with no federal health limit.
Hard water explainedLargest water systems
- CincinnatiCINCINNATI PUBLIC WATER SYSTEM · OH3102612800,000 served
- HarrisonHARRISON CITY PWS · OH310081211,600 served
- ReadingREADING CITY PWS · OH31018129,506 served
Frequently asked
How does Hamilton County tap water compare across cities?
PurityMap ranks 3 cities in Hamilton County by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is Harrison's main water system: HARRISON CITY PWS · PWSID OH3100812 · Purity Score 100 (Excellent) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.
How many Hamilton County cities had a PFAS sample above a 2024 EPA limit?
1 of 3 Hamilton County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing, including Cincinnati (PFOS 6.1 ng/L). That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation. PFAS were detected at any level in 2.
Is there lead in Hamilton County tap water?
Utilities report lead as a 90th-percentile result from home taps. 2 of 3 Hamilton County cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.
Does Hamilton County have hard water?
Hardness is published in utility water-quality reports for 1 Hamilton County city on record; the hardest is Cincinnati at 7.8 grains per gallon. Hardness affects scale and appliances; it is not a health finding.
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