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EPA ID OH3102612 · checked 16 Oct 2026

Cincinnati tap water: what EPA testing found

Greater Cincinnati Water Works (EPA record: CINCINNATI PUBLIC WATER SYSTEM) serves 800,000 people in OH from surface water.

What the data shows

PFAS and lithium (EPA UCMR 5)

180 results from 2 sampling points, 10 May 2023 to 5 Feb 2024. Averages count results below EPA’s reporting level as zero, as the PFAS rule does. Every number links to EPA’s UCMR 5 Data Finder (search PWSID OH3102612). Limits: EPA PFAS rule.

ContaminantDetected inHighest resultAverageEPA limit
PFOA0 of 6not detected0 ng/L4 ng/L
PFOS2 of 66.1 ng/L1.72 ng/L4 ng/L
PFHxS0 of 6not detected0 ng/L10 ng/L*
PFNA0 of 6not detected0 ng/L10 ng/L*
HFPO-DA0 of 6not detected0 ng/L10 ng/L*
PFBS2 of 64.1 ng/L1.3 ng/Lnone
PFBA2 of 65.2 ng/L1.72 ng/Lnone
Lithium0 of 6not detected0 µg/Lnone (screening level 10 µg/L)

* PFHxS, PFNA and HFPO-DA limits (and the PFAS hazard index) are in the rule, but EPA proposed on 20 May 2026 to rescind them; not final as of 16 Oct 2026. UCMR 5 results are screening data, not compliance results: compliance uses quarterly running averages from 2029. Source file: EPA UCMR 5 occurrence data (dated 15 Oct 2026).

Sampling points averaging above a limit

FacilityWaterSamplesPFOA avgPFOS avgAbove
Bolton Plant (54745)ground20 ng/L5.15 ng/LPFOS

Health-based violations since 2016

None in EPA’s SDWIS data.

Source: EPA SDWIS via Envirofacts and the ECHO report for OH3102612, retrieved 16 Oct 2026.

Hardness

7.4 grains per gallon (Richard Miller plant, about 88% of the water; Bolton plant areas about 8.2 gpg, 2025), from the utility’s water report checked 16 Oct 2026. Size a softener for this water.

Plant, source or areaServesGrains per gallon
Richard Miller Treatment Plant (Ohio River)about 88% of GCWW's drinking water (report p.2)7.37
Charles M. Bolton Plant (Great Miami Buried Valley Aquifer)–8.19

From the same report. Which plant or source serves an address depends on where it is; the utility’s report explains its areas.

Places and ZIP codes served

Cincinnati, Addyston, Cleves, Fairfield, Hamilton, Harrison, Loveland, Mason, Miamitown, North Bend, Terrace Park, West Chester.

45001 45002 45013 45014 45030 45040 45041 45052 45069 45140 45174 45202 45203 45204 45205 45206 45207 45208 45209 45211 45212 45213 45214 45215 45216 45217 45218 45219 45220 45221 45223 45224 45225 45226 45227 45229 45230 45231 45232 45233 45236 45237 45238 45239 45240 45241 45242 45243 45244 45245 45246 45247 45248 45249 45251 45252 45255

ZIP codes the system reported to EPA for UCMR 5; place names from GeoNames (CC BY 4.0). A ZIP code can be split between systems.