Water system
Warren County
EPA ID OH8301512 · Warren County · 81,975 people served · owned by a local government
Warren County treats its own water from Wells in the Little Miami and Great Miami river valley aquifers.
The system's record
- Aquifer
- Buried Valley Aquifer System - Little Miami valley (Renneker plant) plus Great Miami valley (Franklin plant)
- Water bodies
- Little Miami River, Great Miami River
- Active wells
- 24
- Serves
- 81,975 people · Warren County
- EPA ID
- OH8301512
About this area's water
Did you know
- Warren County reports no lead, no galvanized-requiring-replacement, and no unknown-material service lines anywhere in its distribution system.
- The system is a patchwork of five sub-systems: Franklin-Clearcreek and Richard Renneker on county wells, Socialville on Cincinnati water, and Pennyroyal and Sharts Road on Springboro water.
- A November 2024 lab mix-up - nitrite tested instead of nitrate - drew an Ohio EPA monitoring violation even though the retest came back below the nitrate limit.
- The 24 county wells pump more than 2 billion gallons a year, and the finished water averages 140 mg/L of hardness, about 8 grains.
History5
- 1960sThe Warren County Water & Sewer Department began operating and says it has never permitted lead pipe in its mains or on customer service laterals.
- 2022Softening started up at both plants after a corrosion control study done with Ohio EPA, and nanofiltration membrane treatment was added.
- January 2023Nanofiltration membrane construction was completed, cutting hardness and improving removal of PFAS, pesticides and herbicides.
- July 2024Ohio EPA approved merging the Franklin-Clearcreek and Richard Renneker systems into the new Warren County Public Water System.
- April 2025The county began building ion exchange PFAS treatment at the Renneker plant, scheduled to finish that November.
Treatment & pressure
How it is treated
24 wells in 5 wellfields feed two county plants: Franklin Area (7 wells) and Renneker (4 wellfields). Softening, nanofiltration membranes, pH control with sodium hydroxide and orthophosphate, then fluoride and chlorine; Renneker adds ion exchange for PFAS.
Water pressure
Not published; the county uses elevated storage such as the 20 Mile elevated tower rather than publishing a system average.
What it costs
$5.70 per 1,000 gallons
2026 water: $34.20 bimonthly minimum covers 0-6,000 gal, then $5.70 per 1,000 gal, plus a $5.00 bimonthly repair/replacement charge. Sewer billed separately.
Water quality & impurities6
| Contaminant | Level | Limit | Year |
|---|---|---|---|
| PFAS (six federally regulated compounds) Non-detect in treated water in both 2023 and 2024 after the nanofiltration upgrade. | ND ppt | EPA MCLs… | 2024 |
| Perfluoropentanoic acid (PFPeA), UCMR5 Detected at the Franklin-Clearcreek plant; non-detect in the Socialville system. | 0.0017 avg… ppb | unregulated… | 2024 |
| PFOA, UCMR5 Non-detect at both Franklin-Clearcreek and Socialville. | ND ppb | unregulated… | 2024 |
| PFOS, UCMR5 Non-detect at both Franklin-Clearcreek and Socialville. | ND ppb | unregulated… | 2024 |
| Lithium, UCMR5 Non-detect at both sampling points; no MCL exists for lithium. | ND ppb | unregulated… | 2024 |
| Nitrate Nov. 2024 lab ran nitrite not nitrate; the late retest was below the MCL but drew a monitoring violation. | below MCL ppm | 10 | 2024 |
EPA compliance record
Lead at the tap: 90th-percentile result 1.3 ppb in 2026 (action level 15 ppb).
EPA record: no health-based violations since 2015.
2 violations of any kind logged since 2020: 2 for a report, record or notice that was missing, late or incomplete (the yearly water quality report, a public notice, lead line records).
Projects & plans4
Recent and current work
- Nanofiltration membrane treatment at both plants · 2023 · completed
Added in 2022 and completed January 2023 at Renneker and Franklin Area; cuts hardness and removes PFAS, pesticides and herbicides. - Renneker Water Treatment Plant ion exchange PFAS system · 2025 · completed
Anion exchange added to the existing nanofiltration building; AECOM engineer, Shook Construction builder. Cost not published. - Franklin-Clearcreek / Richard Renneker system merger · 2024 · completed
Ohio EPA approved consolidation into a single Warren County Public Water System in July 2024.
Planned or needed
- Future capital program
We found no public Warren County capital improvement plan or Ohio EPA loan-list entry for future water projects.
Supply stress
Ohio EPA classes the Great and Little Miami buried valley aquifers highly susceptible, given contaminant sources in the protection areas. Low PFAS at the Renneker wellfields drove nanofiltration then ion exchange. 15% of customers drink Springboro water, whose aquifer sits under 5 ft of cover.
Sewers
Sanitary
The Warren County Water & Sewer Department also runs county sanitary sewer. 2026 sewer rates are a $34.32 bimonthly minimum for 0-6,000 gal then $5.72 per 1,000 gal, with a separate Carlisle-area sewer-only rate.
Sourcesverified
Compiled from the utility's own reports and public records, then independently re-checked against primary sources.
Main supplier in 2 ZIP codes
Serves
Main water supplier in 2 ZIP codes
- 45034 · Deerfield Township and Kings Mills100% of residents
- 45039 · Hamilton Township and Maineville98% of residents
Also present in 4 more ZIP codes
- 45065 · South Lebanon43% of residents
- 45152 · Hamilton Township and Morrow17% of residents
- 45140 · Miami Township and Loveland7% of residents
- 45040 · Mason2% 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
Warren County does not buy water from another system on record; it treats its own source water.
1 system on record buys water from Warren County: South Lebanon No 2.
What the records show about Warren County
Who runs it
EPA's record describes Warren County as owned by a local government. It has 30,361 service connections and serves 81,975 people.
EPA classes it as a community water system, one that serves the same residents all year.
Source: EPA Safe Drinking Water Information System (SDWIS), water system record.
How the water is treated
EPA's treatment table registers these steps for Warren County: aeration, corrosion control, chlorine disinfection, dechlorination, fluoridation, ion-exchange softening, membrane filtration, 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 Warren County since 2015.
EPA logs 2 violations of any kind since 2020: 2 for a report, record or notice that was missing, late or incomplete (the yearly water quality report, a public notice, lead line records).
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 Warren County was 1.3 ppb, under both the current 15 ppb action level and the 10 ppb level that applies from 2027.
The highest result on file is 7 ppb, in the period ending December 2019.
EPA has 13 sampling periods on file for Warren County since 2016, the first ending in 2016; no period was above 10 ppb.
Every water system has to inventory its service lines, the pipes from the main to each building. In the inventory Warren County sent EPA, 28,919 lines are counted.
| Material | Lines |
|---|---|
| Lead | 0 |
| Galvanized, needing replacement | 0 |
| Unknown material | 0 |
| Not lead | 28,919 |
| All lines | 28,919 |
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 2 samples of the water entering the pipes of Warren County in 2023 and measured 29 PFAS. No PFAS was detected, PFOA and PFOS (federal limit 4 ng/L each) among them.
Ohio EPA's own statewide sampling tested 1 plant of Warren County (latest sample March 2021). The highest result was PFOS at 8.6 ppt (ppt is the same unit as ng/L), against Ohio's action level of 70 ppt. Those action levels are the ones Ohio EPA used for the survey; the 2024 federal limit for PFOA and PFOS is 4 ng/L.
Ohio EPA's current sampling status map lists 2 plants of Warren County as sampled, most recently July 2026.
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 Warren County's samples in 2019, the last year it was sampled, was 21.1 µg/L. The worst yearly average was 24.6 µg/L and the highest single sample was 40.2 µg/L, from 70 samples taken from 2012 to 2019.
For HAA5, the average in the last year sampled was 2.8 µg/L. The worst yearly average was 6.1 µg/L and the highest single sample was 15.7 µg/L, from 71 samples.
| Byproduct | Limit | Latest yearly average | Worst yearly average | Highest sample | Samples |
|---|---|---|---|---|---|
| TTHM | 80 µg/L | 21.1 µg/L (2019) | 24.6 µg/L | 40.2 µg/L | 70 |
| HAA5 | 60 µg/L | 2.8 µg/L | 6.1 µg/L | 15.7 µg/L | 71 |
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 8 samples was 0.91 mg/L (as nitrogen) in 2012; in 2019, the last year sampled, the highest was 0.88 mg/L. No sample was over the limit of 10 mg/L. Nitrate above 10 is unsafe for infants.
Arsenic was not detected in 3 samples (limit 10 µg/L).
| Contaminant | Samples | Highest result | Limit | Samples over limit |
|---|---|---|---|---|
| Nitrate (as nitrogen) | 8 | 0.91 mg/L | 10 mg/L | 0 |
| Arsenic | 3 | 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 Warren County 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 3 samples each.
| Compound | Limit | Samples | Detected in | Highest result | Samples over limit |
|---|---|---|---|---|---|
| Benzene | 5 µg/L | 3 | 0 of 3 | not detected | 0 |
| Carbon tetrachloride | 5 µg/L | 3 | 0 of 3 | not detected | 0 |
| 1,2-dichloroethane | 5 µg/L | 3 | 0 of 3 | not detected | 0 |
| Trichloroethylene (TCE) | 5 µg/L | 3 | 0 of 3 | not detected | 0 |
| Tetrachloroethylene (PCE) | 5 µg/L | 3 | 0 of 3 | not detected | 0 |
| Vinyl chloride | 2 µg/L | 3 | 0 of 3 | 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 3 of 3 samples, highest 98.1 µg/L (limit 2,000). Not detected: atrazine, alachlor, chromium, cadmium, mercury, selenium, and thallium, in 3 samples each.
| Substance | Kind | Limit | Samples | Detected in | Highest result | Samples over limit |
|---|---|---|---|---|---|---|
| Atrazine | Farm chemical | 3 µg/L | 3 | 0 of 3 | not detected | 0 |
| Alachlor | Farm chemical | 2 µg/L | 3 | 0 of 3 | not detected | 0 |
| Chromium | Metal | 100 µg/L | 3 | 0 of 3 | not detected | 0 |
| Cadmium | Metal | 5 µg/L | 3 | 0 of 3 | not detected | 0 |
| Barium | Metal | 2,000 µg/L | 3 | 3 of 3 | 98.1 µg/L | 0 |
| Mercury | Metal | 2 µg/L | 3 | 0 of 3 | not detected | 0 |
| Selenium | Metal | 50 µg/L | 3 | 0 of 3 | not detected | 0 |
| Thallium | Metal | 2 µg/L | 3 | 0 of 3 | 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 Warren County 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, 3 of 3,248 routine total coliform samples taken in the distribution system at Warren County tested positive (0.09%); in 2019, the last year on file, 0 of 480 did. E. coli was never found in the 5 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 Warren County adjusts the fluoride level to the recommended level for preventing tooth decay.
EPA's treatment table lists fluoridation among the steps at Warren County.
Measured fluoride: 1.1 mg/L on average at the plant's entry points in 2019 (in the range dentists aim for); samples ran from 0.92 to 1.1 mg/L across 3 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 2 UCMR 5 samples at Warren County, last sampled in 2023 (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.
Water and sewer bills
Ohio EPA's 2023 rate survey puts the water bill at Warren County for a household using 5,000 gallons a month at $282 a year, about $24 a month.
The sewer bill in the same survey is $280 a year at 5,000 gallons a month.
| Use | Water, per year | Sewer, per year |
|---|---|---|
| 2,500 gallons a month | $169 | $168 |
| 5,000 gallons a month | $282 | $280 |
| 8,000 gallons a month | $451 | $448 |
The survey lists it as “Warren County Water & Sewer”. 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 Warren County comes from the utility's own map.
Counting the people who live in the ZIP codes it overlaps, this atlas estimates 38,225 residents are inside the boundary, 47% of the 81,975 people Warren County reports serving. With so much of its territory outside the polygon, part of the system shows on the map as private wells.
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 — 6 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 OH8301512 (EPA ECHO).
Warren County's own pages: data.epa.gov, edocpub.epa.ohio.gov, shookconstruction.com
