Water system
Westerville City
EPA ID OH2503411 · Franklin County · 39,000 people served · owned by a local government
Westerville City treats its own water from Alum Creek + wells.
The system's record
- Water bodies
- Alum Creek
- Raw intakes
- Westerville Alum Creek Inta
- Active wells
- 3
- Serves
- 39,000 people · Franklin County
- EPA ID
- OH2503411
About this area's water
Did you know
- Westerville was the first community in Ohio to fluoridate its drinking water, starting in 1951.
- It is a lime-softening plant: hardness is cut to about 111 mg/L (6.5 grains per gallon) on average before the water leaves the plant.
- At $36 a month in 2024, Westerville's average residential water bill was among the lowest in central Ohio - below Reynoldsburg ($52), Upper Arlington ($51) and Dublin ($48).
- Westerville keeps an emergency connection to Columbus's water system but has not needed to use it since 1994.
History5
- 1924City opened its first Alum Creek water treatment plant, ending the community's reliance on well water for drinking supply.
- 1951Westerville became the first community in Ohio to fluoridate its drinking water.
- 1970-1975US Army Corps of Engineers built Alum Creek Dam upstream of the city; authorized by Congress in 1962, construction began 1970, dam completed 1975.
- 1977A federal grant funded a wastewater collection upgrade; two collector sewers were added and all known sanitary sewer overflows were permanently blocked.
- 2024Centennial of the Alum Creek plant on Dec. 30; the Westerville Public Library and History Museum mounted an exhibit on the milestone.
Treatment & pressure
How it is treated
Plant at 312 W. Main St., licensed for 7.5 MGD: ferric chloride coagulation, lime and caustic soda softening, carbon dioxide for pH, rapid sand filters, GAC filters, sodium hypochlorite, then phosphate for corrosion control and fluoride. PAC and permanganate as needed.
Water pressure
Not published. The city reports no system-wide average pressure or pressure-zone figures; treated water is stored in a clearwell and pumped to elevated storage tanks.
What it costs
$8.14 per 1,000 gallons
Typical household bill about $36 a month for water.
May 2026: $11.22/month minimum (includes first 2 ccf), then $6.09/ccf = $8.14 per 1,000 gal; falls to $5.00 and $3.46/ccf at higher tiers.
Water quality & impurities8
| Contaminant | Level | Limit | Year |
|---|---|---|---|
| Total trihalomethanes (TTHM) Locational running annual average; range 28.6-83.4 ppb - closest result to any MCL. | 66.8 ppb | 80 | 2024 |
| Haloacetic acids (HAA5) Locational running annual average; range 11.9-28.7 ppb. | 19.1 ppb | 60 | 2024 |
| Lead 90th percentile; 0 of 37 samples above the action level. | 1.5 ppb | 15 (action… | 2023 |
| Copper 90th percentile; 0 of 37 samples above the action level. | 0.0479 ppm | 1.3 (action… | 2023 |
| Nitrate Range ND-0.9 ppm; well below the MCL. | 0.9 ppm | 10 | 2024 |
| Fluoride Added at the plant; range 0.82-1.07 ppm. | 0.97 ppm | 4 | 2024 |
| Barium Erosion of natural deposits; about 1% of the MCL. | 0.02 ppm | 2 | 2024 |
| Turbidity Highest 2024 result; 100% of monthly samples met the limit. | 0.11 NTU | 0.3 (treatment… | 2024 |
EPA compliance record
Lead at the tap: 90th-percentile result 1.5 ppb in 2023 (action level 15 ppb).
EPA health-based violations since 2015:
- 2016Total trihalomethanes (TTHM) · above the legal limit on average · measured 0.09 MG/L (limit 0.08 MG/L) · returned to compliance
- 2015Total trihalomethanes (TTHM) · above the legal limit on average · measured 0.09 MG/L (limit 0.08 MG/L) · returned to compliance
EPA's count of 3 includes 1 repeat quarterly violation of the problems listed.
Projects & plans2
Recent and current work
- Lead and galvanized service line inventory · 2024 · completed
Required inventory published as a searchable online map; residents asked to self-report or scratch-test lines of unknown material.
Planned or needed
- Galvanized water service line replacement · 2027-2034 · planned
City replacement plan required by fall 2027 and replacements complete by 2034; the city replaces the public portion, the owner the private portion.
Supply stress
Both Alum Creek and the Alum Creek Valley Aquifer are classified highly susceptible to contamination - oil and gas wells, leaking tanks, landfills and salt storage sit in the source area. Peak day 5.15 MGD against 7.5 MGD plant capacity; the Columbus emergency tie is unused since 1994.
Sewers
Sanitary
Westerville maintains the collection system (3,109 manholes, one lift station at Mariners Cove) but owns no treatment plant: all wastewater is treated by the City of Columbus or the Delaware County sewage district under contract. A 1977 grant-funded upgrade blocked all known overflows; none found since.
Storm
Fully separate storm system - 133 miles of storm sewer and 43 outfalls to Alum Creek and Big Walnut Creek under an Ohio EPA Phase II MS4 permit. No separate residential stormwater fee appears on the city rate sheet.
Sourcesverified
Compiled from the utility's own reports and public records, then independently re-checked against primary sources.
Main supplier in 1 ZIP code
Serves
Main water supplier in 1 ZIP code
- 43081 · Westerville46% of residents
Also present in 1 more ZIP code
- 43082 · Genoa Township and Westerville28% 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
Westerville City does not buy water from another system on record; it treats its own source water.
No other system is on record buying water from Westerville City.
What the records show about Westerville City
Who runs it
EPA's record describes Westerville City as owned by a local government. It has 13,624 service connections and serves 39,000 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 419-782-1886.
Source: EPA Safe Drinking Water Information System (SDWIS), water system record.
How the water is treated
EPA's treatment table registers these steps for Westerville City: 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 counts 3 health-based violations for Westerville City since 2015. Health-based means a contaminant above its legal limit or a required treatment step not carried out. They fall into 2 separate problems (one contaminant or rule in one year); the table lists them all.
EPA logs a violation for each compliance period a problem lasts, so the count of 3 includes 1 repeat entry of the problems listed.
EPA logs no violations of any kind for Westerville City since 2020.
| Year | Contaminant or rule | Kind | Measured | Limit | Status in EPA's record |
|---|---|---|---|---|---|
| 2016 | Total trihalomethanes (TTHM) | above the legal limit on average | 0.09 mg/L | 0.08 mg/L | returned to compliance |
| 2015 | Total trihalomethanes (TTHM) | above the legal limit on average | 0.09 mg/L | 0.08 mg/L | returned to compliance |
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 December 2023, the 90th-percentile lead result at Westerville City was 1.5 ppb, under both the current 15 ppb action level and the 10 ppb level that applies from 2027.
EPA has 5 sampling periods on file for Westerville City since 2016, the first ending in 2017; 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 Westerville City sent EPA, 12,547 lines are counted.
| Material | Lines |
|---|---|
| Lead | 0 |
| Galvanized, needing replacement | 21 |
| Unknown material | 567 |
| Not lead | 11,959 |
| All lines | 12,547 |
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 4 samples of the water entering the pipes of Westerville City in 2024 to 2025 and measured 29 PFAS.
PFOA and PFOS were not detected, against a federal limit of 4 ng/L each.
The highest PFAS result was PFBA 5.6 ng/L.
Ohio EPA's own statewide sampling tested 1 plant of Westerville City (latest sample October 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 1 plant of Westerville City as sampled, most recently August 2025; it flags PFAS detected at the plant.
| Compound | Highest result | Federal limit |
|---|---|---|
| PFOA | not detected | 4 ng/L |
| PFOS | not detected | 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 Westerville City's samples in 2019, the last year it was sampled, was 50.5 µg/L. The worst yearly average was 68.5 µg/L and the highest single sample was 146 µg/L, from 128 samples taken from 2012 to 2019.
For HAA5, the average in the last year sampled was 13.1 µg/L. The worst yearly average was 49.3 µg/L and the highest single sample was 80.3 µg/L, from 128 samples.
| Byproduct | Limit | Latest yearly average | Worst yearly average | Highest sample | Samples |
|---|---|---|---|---|---|
| TTHM | 80 µg/L | 50.5 µg/L (2019) | 68.5 µg/L | 146 µg/L | 128 |
| HAA5 | 60 µg/L | 13.1 µg/L | 49.3 µg/L | 80.3 µg/L | 128 |
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 96 samples was 1.64 mg/L (as nitrogen), in 2019, the last year sampled. No sample was over the limit of 10 mg/L. Nitrate above 10 is unsafe for infants.
Arsenic was not detected in 8 samples (limit 10 µg/L).
| Contaminant | Samples | Highest result | Limit | Samples over limit |
|---|---|---|---|---|
| Nitrate (as nitrogen) | 96 | 1.64 mg/L | 10 mg/L | 0 |
| Arsenic | 8 | 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.
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 8 samples each.
| Compound | Limit | Samples | Detected in | Highest result | Samples over limit |
|---|---|---|---|---|---|
| Benzene | 5 µg/L | 8 | 0 of 8 | not detected | 0 |
| Carbon tetrachloride | 5 µg/L | 8 | 0 of 8 | not detected | 0 |
| 1,2-dichloroethane | 5 µg/L | 8 | 0 of 8 | not detected | 0 |
| Trichloroethylene (TCE) | 5 µg/L | 8 | 0 of 8 | not detected | 0 |
| Tetrachloroethylene (PCE) | 5 µg/L | 8 | 0 of 8 | not detected | 0 |
| Vinyl chloride | 2 µg/L | 8 | 0 of 8 | 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: atrazine in 7 of 25 samples, highest 0.6 µg/L (limit 3); barium in 7 of 8 samples, highest 19.7 µg/L (limit 2,000). Not detected: alachlor in 25 samples, chromium in 8 samples, cadmium in 8 samples, mercury in 8 samples, selenium in 8 samples, thallium in 8 samples.
| Substance | Kind | Limit | Samples | Detected in | Highest result | Samples over limit |
|---|---|---|---|---|---|---|
| Atrazine | Farm chemical | 3 µg/L | 25 | 7 of 25 | 0.6 µg/L | 0 |
| Alachlor | Farm chemical | 2 µg/L | 25 | 0 of 25 | not detected | 0 |
| Chromium | Metal | 100 µg/L | 8 | 0 of 8 | not detected | 0 |
| Cadmium | Metal | 5 µg/L | 8 | 0 of 8 | not detected | 0 |
| Barium | Metal | 2,000 µg/L | 8 | 7 of 8 | 19.7 µg/L | 0 |
| Mercury | Metal | 2 µg/L | 8 | 0 of 8 | not detected | 0 |
| Selenium | Metal | 50 µg/L | 8 | 0 of 8 | not detected | 0 |
| Thallium | Metal | 2 µg/L | 8 | 0 of 8 | not detected | 0 |
Non-detects count as zero in the highest-result column.
Source: EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, finished water.
Bacteria in the pipes
From 2012 to 2019, 4 of 4,031 routine total coliform samples taken in the distribution system at Westerville City tested positive (0.1%); in 2019, the last year on file, 0 of 504 did. E. coli was never found in the 4 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 Westerville City adjusts the fluoride level to the recommended level for preventing tooth decay.
EPA's treatment table lists fluoridation among the steps at Westerville City.
Measured fluoride: 0.87 mg/L on average at the plant's entry points in 2019 (in the range dentists aim for); samples ran from 0.78 to 0.99 mg/L across 8 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 4 UCMR 5 samples at Westerville City, last sampled in 2025 (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 1 time in 189 raw-water samples, across 1 bloom season (2022); the highest raw-water result was 0.503 µg/L on November 7, 2022. There has been no raw-water detection since 2024.
Microcystin was never detected in treated water (195 samples).
In all, 384 samples from 2016 to 2026, the latest on August 12, 2026.
| Water | Samples | Detections | Highest result |
|---|---|---|---|
| Raw water, at the intake | 189 | 1 | 0.503 µg/L |
| Treated water | 195 | 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 Westerville City for a household using 5,000 gallons a month at $403 a year, about $34 a month.
| Use | Water, per year | Sewer, per year |
|---|---|---|
| 2,500 gallons a month | $198 | not on file |
| 5,000 gallons a month | $403 | not on file |
| 8,000 gallons a month | $649 | not on file |
The survey lists it as “Westerville”. 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 Westerville City comes from the utility's own map.
Counting the people who live in the ZIP codes it overlaps, this atlas estimates 39,052 residents are inside the boundary, 100% of the 39,000 people Westerville City 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 — 2 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 OH2503411 (EPA ECHO).
Westerville City's own pages: westerville.org, 1808delaware.com
