Water system
Cincinnati Public Water System
EPA ID OH3102612 · Hamilton County · 750,200 people served · owned by a local government
Cincinnati Public Water System treats its own water from Ohio River (Miller Plant, ~88%) plus Great Miami Buried Valley Aquifer wells (~12%).
The system's record
- Aquifer
- Great Miami Buried Valley Aquifer
- Water bodies
- Ohio River
- Raw intakes
- Cincinnati Miller Ohio River
Cincinnati Miller Ohio River S - Active wells
- 13
- Serves
- 750,200 people · Hamilton County
- EPA ID
- OH3102612
About this area's water
Did you know
- The Richard Miller plant is one of only a few in the country that pairs granular activated carbon with ultraviolet disinfection, and the GAC is regenerated on site in the plant's own reactivation furnace.
- Cincinnati's 1839 purchase of a private water company for $300,000 made it Ohio's first municipally owned water system.
- Rather than bury the problem in a storage tunnel, MSD dug up a mile of the long-buried Lick Run stream as green infrastructure, cutting about 400 million gallons of overflow a year.
- The city's two plants could hardly be more different: Miller filters river water through carbon and UV, while Bolton simply softens well water with lime.
History5
- 1821The Front Street Pumping Station begins operating for the private Cincinnati Manufacturing Company, chartered in 1817; it served until Nov. 1907.
- 1839On June 25 the City of Cincinnati buys the water works for $300,000, becoming Ohio's first municipally owned water utility.
- 1907On Oct. 22 the 'New Works' on Kellogg Ave., begun in 1898 about ten miles upstream, starts continuous rapid-sand filtration.
- 2009MSD begins implementing its federal Clean Water Act wet weather program, one of the largest public works efforts in the region's history.
- 2024PFOA and PFOS at the Bolton groundwater plant test above EPA's new 4 ppt limits, starting a compliance push ahead of the 2029 deadline.
Treatment & pressure
How it is treated
About 88% of supply is Ohio River water treated at the Richard Miller plant by coagulation, flocculation, sedimentation, rapid sand filtration, granular activated carbon, UV light and chlorine, with fluoride. The other 12% is Bolton well water, lime softened and chlorinated, with no GAC.
Water pressure
Not published as a system average. GCWW serves a hilly, multi-elevation area with numerous pressure districts, pump stations and storage tanks.
What it costs
GCWW publishes an annual 'Cost of Your Water' residential rate sheet; we found no per-1,000-gallon rate or effective year on its website.
Water quality & impurities7
| Contaminant | Level | Limit | Year |
|---|---|---|---|
| TTHM Range 14.0-60.3. Below MCL, no violation. | 49.6 ppb | 80 | 2024 |
| HAA5 Range 2.0-13.2. Far below MCL, helped by GAC treatment. | 9.9 ppb | 60 | 2024 |
| Lead (90th percentile) Two monitoring periods; well below the action level, though 1 of 107 first-period samples exceeded it. | 1.12-2.32 ppb | 15 | 2024 |
| Copper (90th percentile) No sites above the action level in either monitoring period. | 0.019-0.024 ppm | 1.3 | 2024 |
| PFOA Bolton groundwater plant only; above the new EPA MCL. Miller plant stays below. | up to 4.7 ppt | 4 | 2024 |
| PFOS Bolton plant only; above the new EPA MCL, compliance required by 2029. | up to 6.1 ppt | 4 | 2024 |
| Fluoride Range 0.72-0.96; added for dental health, well under the MCL. | 0.90 ppm | 4 | 2024 |
EPA compliance record
Lead at the tap: 90th-percentile result 2.1 ppb in 2026 (action level 15 ppb).
EPA record: no health-based violations since 2015.
Projects & plans3
Recent and current work
- Lick Run Greenway · 2021 · completed
Daylighted a buried stream in South Fairmount; eliminates roughly 400 million gal/yr of combined sewer overflow to Mill Creek. - MSD Wet Weather Program (consent decree) · 2009-present · under construction
Has cut annual sewer overflow volume from about 14 billion to 5.9 billion gallons systemwide.
Planned or needed
- Bolton plant PFAS treatment · planned
GCWW has grant money to study treatment options and says it will install whatever is needed to meet the 2029 PFAS standards.
Supply stress
The Ohio River source is high-volume and drought-resilient, and the Miller plant's GAC gives it a strong barrier against spills and PFAS. The live concern is the Bolton groundwater plant, where PFOA and PFOS exceed the new federal limits for roughly 12% of GCWW customers ahead of the 2029 deadline.
Sewers
Sanitary
The Metropolitan Sewer District of Greater Cincinnati (MSD), a county-city partnership, provides sanitary sewers and wastewater treatment. MSD works under a federal Clean Water Act consent decree and has been implementing its wet weather program since 2009 to cut combined sewer overflows into Mill Creek and other waterways.
Storm
Much of the older urban core uses combined sanitary/storm sewers. MSD's wet weather plan mixes green infrastructure like the Lick Run Greenway with conventional separation and storage to reduce overflow-driven flooding.
Sourcesverified
Compiled from the utility's own reports and public records, then independently re-checked against primary sources.
Main supplier in 47 ZIP codes
Serves
Main water supplier in 47 ZIP codes
- 45041 · Whitewater Township and Miamitown100% of residents
- 45051 · Delhi Township and Mount Saint Joseph100% of residents
- 45202 · Cincinnati100% of residents
- 45203 · Cincinnati100% of residents
- 45204 · Cincinnati100% of residents
- 45205 · Cincinnati100% of residents
- 45206 · Cincinnati100% of residents
- 45207 · Cincinnati100% of residents
- 45208 · Cincinnati100% of residents
- 45211 · Cincinnati100% of residents
- 45213 · Cincinnati100% of residents
- 45214 · Cincinnati100% of residents
- 45216 · Cincinnati100% of residents
- 45217 · Saint Bernard and Cincinnati100% of residents
- 45218 · Greenhills and Cincinnati100% of residents
- 45219 · Cincinnati100% of residents
- 45220 · Cincinnati100% of residents
- 45223 · Cincinnati100% of residents
- 45224 · Cincinnati100% of residents
- 45225 · Cincinnati100% of residents
- 45226 · Cincinnati100% of residents
- 45227 · Cincinnati100% of residents
- 45229 · Cincinnati100% of residents
- 45230 · Anderson Township and Cincinnati100% of residents
- 45232 · Cincinnati100% of residents
- 45233 · Delhi Township and Cincinnati100% of residents
- 45238 · Delhi Township and Cincinnati100% of residents
- 45239 · Colerain Township and Cincinnati100% of residents
- 45240 · Forest Park and Cincinnati100% of residents
- 45247 · Green Township and Cincinnati100% of residents
- 45248 · Green Township and Cincinnati100% of residents
- 45251 · Colerain Township and Cincinnati100% of residents
- 45252 · Colerain Township and Cincinnati100% of residents
- 45267 · Cincinnati100% of residents
- 45231 · Springfield Township and Cincinnati99% of residents
- 45209 · Cincinnati98% of residents
- 45236 · Sycamore Township and Cincinnati96% of residents
- 45242 · Blue Ash and Cincinnati96% of residents
- 45237 · Cincinnati95% of residents
- 45249 · Symmes Township and Cincinnati94% of residents
- 45246 · Springdale and Cincinnati85% of residents
- 45255 · Anderson Township and Cincinnati70% of residents
- 45241 · Sharonville and Cincinnati67% of residents
- 45002 · Miami Township and Cleves64% of residents
- 45040 · Mason59% of residents
- 45244 · Anderson Township and Cincinnati54% of residents
- 45215 · Reading and Cincinnati33% of residents
Also present in 9 more ZIP codes
- 45052 · Miami Township and North Bend48% of residents
- 45243 · Madeira and Cincinnati32% of residents
- 45030 · Harrison30% of residents
- 45212 · Norwood and Cincinnati14% of residents
- 45140 · Miami Township and Loveland6% of residents
- 45036 · Lebanon3% of residents
- 45039 · Hamilton Township and Maineville0% of residents
- 45014 · Fairfield0% of residents
- 45013 · Hamilton0% of residents
Population-weighted resident shares; a ZIP code can have more than one system on record. Recomputed from each ZIP's own system list, not from the map's cached footprint.
Buys from · Sells to
Cincinnati Public Water System does not buy water from another system on record; it treats its own source water.
6 systems on record buy water from Cincinnati Public Water System: Lebanon City, Norwood City, Reading City, South Lebanon City, Warren Co. Socialville, Western Water Company.
What the records show about Cincinnati Public Water System
Who runs it
EPA's record describes Cincinnati Public Water System as owned by a local government. It has 244,716 service connections and serves 750,200 people.
EPA classes it as a community water system, one that serves the same residents all year.
EPA's record says it has substantially implemented source water protection under Ohio's program, dating the program from 2023. Its office telephone on EPA's record is 513-591-7968.
Source: EPA Safe Drinking Water Information System (SDWIS), water system record.
How the water is treated
EPA's treatment table registers these steps for Cincinnati Public Water System: corrosion control, coagulation and settling, chlorine disinfection, iron and manganese removal, fluoridation, granular activated carbon, lime softening, powdered activated carbon, and sand or media filtration.
The list is what each system registered with EPA for treatment plants EPA still shows as active, and it can lag a plant upgrade.
Source: EPA Safe Drinking Water Information System (SDWIS) treatment table (EPA Envirofacts, pulled September 2026).
Violations
EPA's record shows no health-based violations for Cincinnati Public Water System since 2015.
EPA logs no violations of any kind for Cincinnati Public Water System since 2020.
Source: EPA Safe Drinking Water Information System (SDWIS) violation records: health-based violations with compliance periods beginning in 2015 or later, all violations from 2020 or later (EPA Envirofacts, pulled September 2026).
Lead and copper at the tap
In the sampling period ending June 2026, the 90th-percentile lead result at Cincinnati Public Water System was 2.1 ppb, under both the current 15 ppb action level and the 10 ppb level that applies from 2027.
The highest result on file is 12.2 ppb, in the period ending December 2019.
EPA has 21 sampling periods on file for Cincinnati Public Water System since 2016, the first ending in 2016; 1 of the 21 periods went above 10 ppb.
Every water system has to inventory its service lines, the pipes from the main to each building. In the inventory Cincinnati Public Water System sent EPA, 238,335 lines are counted.
| Material | Lines |
|---|---|
| Lead | 34,673 |
| Galvanized, needing replacement | 44 |
| Unknown material | 45 |
| Not lead | 203,573 |
| All lines | 238,335 |
Systems sample taps in the homes most likely to have lead pipes or solder. The 90th-percentile result is the level nine in ten of the sampled homes were at or below. Lead comes mostly from service lines and house plumbing, not the source water, so a low result for the system does not clear an old house.
EPA's dashboard status for this inventory: reported all required service line types.
Source: EPA Safe Drinking Water Information System (SDWIS) lead and copper 90th-percentile results (EPA Envirofacts), sampling periods ending 2016 or later; EPA's service line inventory dashboard, Ohio's 2026 Q2 submission.
PFAS
EPA's fifth national round of testing (UCMR 5) took 7 samples of the water entering the pipes of Cincinnati Public Water System in 2023 to 2024 and measured 29 PFAS.
The highest PFOA or PFOS result, 6.1 ng/L, is at or above the federal limit of 4 ng/L that EPA set in 2024. Systems have until 2029 to comply, and in May 2026 EPA proposed letting systems apply for two more years. One sample over the limit is not a violation: compliance is judged on a running annual average.
The highest PFAS results were PFOS 6.1 ng/L, PFBA 5.2 ng/L, and PFBS 4.1 ng/L.
The highest PFOA or PFOS result was measured at Bolton Plant.
The system reported potential PFAS sources near its supply.
Ohio EPA's own statewide sampling tested 2 plants of Cincinnati Public Water System (latest sample March 2020). Not one of the six PFAS tested (PFOA, PFOS, PFHxS, PFNA, GenX and PFBS) was detected.
Ohio EPA's current sampling status map lists 2 plants of Cincinnati Public Water System as sampled, most recently August 2026.
| Compound | Highest result | Federal limit |
|---|---|---|
| PFOA | not detected | 4 ng/L |
| PFOS | 6.1 ng/L | 4 ng/L |
PFAS are the 'forever chemicals' from firefighting foam, plating shops and non-stick coatings. Results are for water leaving the plant, not your tap.
Source: EPA UCMR 5 occurrence data (final release, August 2026); Ohio EPA statewide PFAS sampling, 2019 to 2021, and its sampling status map.
Disinfection byproducts
Chlorine that disinfects water also reacts with organic matter to form byproducts. Two groups have federal limits: total trihalomethanes (TTHM, 80 µg/L) and five haloacetic acids (HAA5, 60 µg/L), judged on running yearly averages at each sampling site.
For TTHM, the average of Cincinnati Public Water System's samples in 2019, the last year it was sampled, was 38.9 µg/L. The worst yearly average was 39.5 µg/L and the highest single sample was 75 µg/L, from 539 samples taken from 2012 to 2019.
For HAA5, the average in the last year sampled was 8.5 µg/L. The worst yearly average was 9.6 µg/L and the highest single sample was 18.8 µg/L, from 540 samples.
| Byproduct | Limit | Latest yearly average | Worst yearly average | Highest sample | Samples |
|---|---|---|---|---|---|
| TTHM | 80 µg/L | 38.9 µg/L (2019) | 39.5 µg/L | 75 µg/L | 539 |
| HAA5 | 60 µg/L | 8.5 µg/L | 9.6 µg/L | 18.8 µg/L | 540 |
A yearly average of 0 means nothing was detected in that year's samples. EPA's file stops at 2019; Ohio EPA's Drinking Water Watch has newer results.
Source: EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, distribution-system samples (non-detects counted as zero).
Nitrate, arsenic and radioactivity
Nitrate: the highest of 119 samples was 1.55 mg/L (as nitrogen) in 2015; in 2019, the last year sampled, the highest was 1.3 mg/L. No sample was over the limit of 10 mg/L. Nitrate above 10 is unsafe for infants.
Arsenic was not detected in 16 samples (limit 10 µg/L).
| Contaminant | Samples | Highest result | Limit | Samples over limit |
|---|---|---|---|---|
| Nitrate (as nitrogen) | 119 | 1.55 mg/L | 10 mg/L | 0 |
| Arsenic | 16 | not detected | 10 µg/L | 0 |
Measured in finished water: at the plant's entry points and in the distribution system; raw well and intake samples are left out. Non-detects count as zero.
EPA's file lumps the entry-point samples of all 2 plants of Cincinnati Public Water System together, so a result over a limit may come from a plant that serves a different part of town.
Source: EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, finished water.
Solvents and fuels
EPA's file holds results for all six solvent and fuel compounds it checked. Benzene, carbon tetrachloride, 1,2-dichloroethane, trichloroethylene, tetrachloroethylene, and vinyl chloride were not detected in 11 samples each.
| Compound | Limit | Samples | Detected in | Highest result | Samples over limit |
|---|---|---|---|---|---|
| Benzene | 5 µg/L | 11 | 0 of 11 | not detected | 0 |
| Carbon tetrachloride | 5 µg/L | 11 | 0 of 11 | not detected | 0 |
| 1,2-dichloroethane | 5 µg/L | 11 | 0 of 11 | not detected | 0 |
| Trichloroethylene (TCE) | 5 µg/L | 11 | 0 of 11 | not detected | 0 |
| Tetrachloroethylene (PCE) | 5 µg/L | 11 | 0 of 11 | not detected | 0 |
| Vinyl chloride | 2 µg/L | 11 | 0 of 11 | not detected | 0 |
"Not detected" means the lab's result was below what its method can measure, not that the compound is absent. Non-detects count as zero in the highest-result column.
Source: EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, finished water.
Farm chemicals and metals
EPA's file holds results for 8 of the nine herbicides and metals it checked. Detected: barium in 16 of 16 samples, highest 54 µg/L (limit 2,000). Not detected: atrazine in 11 samples, alachlor in 11 samples, chromium in 16 samples, cadmium in 16 samples, mercury in 16 samples, selenium in 16 samples, thallium in 16 samples.
| Substance | Kind | Limit | Samples | Detected in | Highest result | Samples over limit |
|---|---|---|---|---|---|---|
| Atrazine | Farm chemical | 3 µg/L | 11 | 0 of 11 | not detected | 0 |
| Alachlor | Farm chemical | 2 µg/L | 11 | 0 of 11 | not detected | 0 |
| Chromium | Metal | 100 µg/L | 16 | 0 of 16 | not detected | 0 |
| Cadmium | Metal | 5 µg/L | 16 | 0 of 16 | not detected | 0 |
| Barium | Metal | 2,000 µg/L | 16 | 16 of 16 | 54 µg/L | 0 |
| Mercury | Metal | 2 µg/L | 16 | 0 of 16 | not detected | 0 |
| Selenium | Metal | 50 µg/L | 16 | 0 of 16 | not detected | 0 |
| Thallium | Metal | 2 µg/L | 16 | 0 of 16 | not detected | 0 |
Non-detects count as zero in the highest-result column.
EPA's file lumps the entry-point samples of all 2 plants of Cincinnati Public Water System together, so a result over a limit may come from a plant that serves a different part of town.
Source: EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, finished water.
Bacteria in the pipes
From 2012 to 2019, 11 of 26,813 routine total coliform samples taken in the distribution system at Cincinnati Public Water System tested positive (0.04%); in 2019, the last year on file, 4 of 3,129 did. E. coli was never found in the 11 samples tested for it.
A positive coliform test is a warning sign, not a violation by itself. E. coli is a sign that human or animal waste may have reached the water. Coliform counts are routine samples only; E. coli counts include repeat samples.
Source: EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, distribution-system presence/absence tests for total coliform and E. coli.
Fluoride
The Ohio Department of Health's report to the CDC (My Water's Fluoride) says Cincinnati Public Water System adjusts the fluoride level to the recommended level for preventing tooth decay.
EPA's treatment table lists fluoridation among the steps at Cincinnati Public Water System.
Measured fluoride: 0.81 mg/L on average at the plant's entry points in 2019 (in the range dentists aim for); samples ran from 0.79 to 0.98 mg/L across 16 samples in 2012 to 2019.
The recommended level for preventing tooth decay is 0.7 mg/L; the federal limit is 4 mg/L. The treatment list is what each system registered with EPA and can lag a plant upgrade.
Source: CDC My Water's Fluoride (fluoridation status as reported by the Ohio Department of Health, fetched September 2026); EPA Safe Drinking Water Information System (SDWIS) treatment table; EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, entry-point fluoride samples.
Lithium
Lithium was not detected in 6 UCMR 5 samples at Cincinnati Public Water System, last sampled in 2024 (the method reports from 9 µg/L).
Lithium is not regulated. EPA's draft health reference level is 10 µg/L, and it occurs naturally in deep groundwater, so well systems in the northwest run highest.
Source: EPA UCMR 5 occurrence data (final release, August 2026), samples from 2023 to 2025.
Algal toxins
Ohio EPA tests for microcystin, a toxin that harmful algal blooms can release, in raw water at the intake and in treated water.
At the intake, microcystin was detected 2 times in 288 raw-water samples, across 1 bloom season (2019); the highest raw-water result was 0.46 µg/L on October 2, 2019. There has been no raw-water detection since 2024.
Microcystin was never detected in treated water (285 samples).
In all, 573 samples from 2016 to 2026, the latest on August 25, 2026.
| Water | Samples | Detections | Highest result |
|---|---|---|---|
| Raw water, at the intake | 288 | 2 | 0.46 µg/L |
| Treated water | 285 | 0 | not detected |
The ten-day advisory levels for treated water are 0.3 µg/L for children under six and 1.6 µg/L for everyone else. Any detection at the intake triggers more frequent testing until two clean weeks.
Source: Ohio EPA public water system harmful algal bloom monitoring, 2016 to present (HAB data, fetched September 2026).
Water and sewer bills
Ohio EPA's 2023 rate survey puts the water bill at Cincinnati Public Water System for a household using 5,000 gallons a month at $378 a year, about $32 a month.
| Use | Water, per year | Sewer, per year |
|---|---|---|
| 2,500 gallons a month | $239 | not on file |
| 5,000 gallons a month | $378 | not on file |
| 8,000 gallons a month | $545 | not on file |
The survey lists it as “Cincinnati”. These are inside-city rates and annual bills at the use shown.
Source: Ohio EPA 2023 Sewer and Water Rate Survey (Ohio State University, May 2025).
How well the service area is mapped
The service area drawn on the map for Cincinnati Public Water System comes from the utility's own map.
Counting the people who live in the ZIP codes it overlaps, this atlas estimates 770,134 residents are inside the boundary, 103% of the 750,200 people Cincinnati Public Water System reports serving.
The resident count is an estimate from 2020 Census ZIP-code populations, not a count of customers.
Source: EPA Service Area Boundaries; resident estimate by this atlas from ZIP-code overlap.
Photograph
On the map
Show this system's territory on the map — 56 ZIP codes in all.
Sources
U.S. EPA SDWIS and Community Water System Service Area Boundaries (v3, 2026), Ohio EPA primacy data, 2020 census blocks: the system serving most residents, traced through purchases to the treating utility; Ohio EPA 2023 Sewer and Water Rate Survey (Ohio State, May 2025) for household bills; Ohio EPA DEFA loan awards since 2016 for the loans paragraph · EPA SDWIS · EPA service area boundaries · Ohio EPA drinking water · Ohio EPA rate survey
EPA's own record for this system: Enforcement and Compliance History report for OH3102612 (EPA ECHO).
Cincinnati Public Water System's own pages: cincinnati-oh.gov
