Water system
Gahanna City
EPA ID OH2501303 · Franklin County · 33,258 people served · owned by a local government
Gahanna City buys its water from Columbus Public Water System.
The system's record
- Aquifer
- Scioto River Valley sand and gravel (buried valley) aquifer
- Water bodies
- Scioto River, Griggs Reservoir, O'Shaughnessy Reservoir, Hoover Reservoir, Big Walnut Creek, Alum Creek
- Raw intakes
- Dublin Rd Scioto River
Hap Cremean Big Walnut
Alum Creek Hoover, Hap Cremean
Doutt Reservoir Scioto - Active wells
- 6
- Serves
- 1,305,946 people · Franklin County
- EPA ID
- OH2504412
About this area's water
Did you know
- Gahanna draws no water of its own at all — 100% of its supply is purchased finished from Columbus, and all of its sewage goes back to Columbus for treatment.
- When Columbus raised Gahanna's wholesale water rate 18% for 2026, the city absorbed part of the hit and passed through a 10% increase instead.
- A Gahanna household using 4,000 gallons a month saw its combined water, sewer and stormwater bill rise $7.46 in 2026.
History3
- 1849Gahanna was founded along Big Walnut Creek, the waterway that still runs through the city.
- 2026Columbus raised Gahanna's wholesale water rate 18% and its sewage treatment rate 8%; Gahanna absorbed part and passed through an overall 6.14% increase.
- 2026Extensive rainfall on and around Saturday, August 22 flooded parts of Gahanna, damaging homes; Governor DeWine sought FEMA assistance for recovery.
Treatment & pressure
How it is treated
Gahanna operates no plant and no wells: it buys 100% finished water from Columbus, which runs three treatment plants and describes a 'multi-barrier approach.' Per SDWIS the ultimate sources are the Scioto River (Griggs and O'Shaughnessy) and Hoover Reservoir on Big Walnut Creek.
Water pressure
Not published; Gahanna's Public Utilities page gives no psi or pressure-zone figures, and delivery pressure is set by the Columbus system feeding it.
What it costs
$11.74 per 1,000 gallons
Typical household bill about $47 a month for water.
2026 residential water: $10.62/1,000 gal operations plus $1.12 capital. Sanitary sewer adds $12.49/1,000 gal. Overall utility increase 6.14%.
Water quality & impurities
EPA compliance record
Lead at the tap: 90th-percentile result 0.5 ppb in 2024 (action level 15 ppb).
EPA record: no health-based violations since 2015.
1 violation of any kind logged since 2020: 1 for a report, record or notice that was missing, late or incomplete (the yearly water quality report, a public notice, lead line records).
EPA compliance record · Columbus Public Water System (treats the water)
Lead at the tap: 90th-percentile result 1.2 ppb in 2023 (action level 15 ppb).
EPA health-based violations since 2015:
- 2016Nitrate · above the legal limit on average · measured 10.5 MG/L (limit 10 MG/L) · returned to compliance
Supply stress
Gahanna has no source of its own — 100% of supply is purchased finished water from Columbus, so both reliability and cost track the Columbus Scioto River/Hoover Reservoir system. In August 2026 extensive rainfall flooded parts of the city, prompting a state request for federal disaster aid.
Sewers
Sanitary
Gahanna owns and maintains its own sanitary collection system and runs a CMOM program, but sends all wastewater to Columbus for treatment at the Jackson Pike and Southerly plants, which serve Columbus plus about 25 contracting suburban communities. 2026 rate: $12.49/1,000 gal.
Storm
Separate storm sewer infrastructure owned by the city and managed by its Engineering Department; stormwater is billed within the utility rates. Extensive August 2026 rainfall caused widespread property damage.
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
- 43230 · Gahanna and Columbus57% of residents
Also present in 1 more ZIP code
- 43054 · Columbus and New Albany8% 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
Gahanna City buys its water from Columbus Public Water System.
No other system is on record buying water from Gahanna City.
What the records show about Gahanna City
Who runs it
EPA's record describes Gahanna City as owned by a local government. It has 10,638 service connections and serves 33,258 people.
EPA classes it as a community water system, one that serves the same residents all year.
Its office telephone on EPA's record is 614-342-4427.
Source: EPA Safe Drinking Water Information System (SDWIS), water system record.
How the water is treated
Gahanna City buys water that Columbus Public Water System treats first, so the steps that count are the seller's. EPA's treatment table registers these steps for Columbus Public Water System: corrosion control, coagulation and settling, chlorine disinfection, iron and manganese removal, fluoridation, ion-exchange softening, lime softening, ozone, powdered activated carbon, sand or media filtration, and ultraviolet disinfection.
Gahanna City adds nothing of its own on that table.
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 Gahanna City since 2015.
EPA logs 1 violation of any kind since 2020: 1 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 December 2024, the 90th-percentile lead result at Gahanna City was 0.5 ppb, under both the current 15 ppb action level and the 10 ppb level that applies from 2027.
EPA has 3 sampling periods on file for Gahanna City since 2016, the first ending in 2018; 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 Gahanna City sent EPA, 10,970 lines are counted.
| Material | Lines |
|---|---|
| Lead | 0 |
| Galvanized, needing replacement | 0 |
| Unknown material | 2,120 |
| Not lead | 8,850 |
| All lines | 10,970 |
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 Gahanna City in 2024 to 2025 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 3 plants of Columbus Public Water System (latest sample October 2020). Not one of the six PFAS tested (PFOA, PFOS, PFHxS, PFNA, GenX and PFBS) was detected.
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 Gahanna City's samples in 2019, the last year it was sampled, was 35.5 µg/L. The worst yearly average was 65.5 µg/L and the highest single sample was 110 µg/L, from 128 samples taken from 2012 to 2019.
For HAA5, the average in the last year sampled was 21.4 µg/L. The worst yearly average was 44.7 µg/L and the highest single sample was 63.4 µg/L, from 128 samples.
| Byproduct | Limit | Latest yearly average | Worst yearly average | Highest sample | Samples |
|---|---|---|---|---|---|
| TTHM | 80 µg/L | 35.5 µg/L (2019) | 65.5 µg/L | 110 µg/L | 128 |
| HAA5 | 60 µg/L | 21.4 µg/L | 44.7 µg/L | 63.4 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
The water Gahanna City buys is treated by Columbus Public Water System, so the results below are Columbus Public Water System's.
Nitrate: the highest of 232 samples was 12.5 mg/L (as nitrogen) in 2015; in 2019, the last year sampled, the highest was 3.6 mg/L. 12 of the samples went over the limit of 10 mg/L. Nitrate above 10 is unsafe for infants.
Arsenic was not detected in 18 samples (limit 10 µg/L).
| Contaminant | Samples | Highest result | Limit | Samples over limit |
|---|---|---|---|---|
| Nitrate (as nitrogen) | 232 | 12.5 mg/L | 10 mg/L | 12 |
| Arsenic | 18 | 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 3 plants of Columbus 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 of Columbus Public Water System.
Solvents and fuels
The water Gahanna City buys is treated by Columbus Public Water System, so the results below are Columbus Public Water System's.
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 18 samples each.
| Compound | Limit | Samples | Detected in | Highest result | Samples over limit |
|---|---|---|---|---|---|
| Benzene | 5 µg/L | 18 | 0 of 18 | not detected | 0 |
| Carbon tetrachloride | 5 µg/L | 18 | 0 of 18 | not detected | 0 |
| 1,2-dichloroethane | 5 µg/L | 18 | 0 of 18 | not detected | 0 |
| Trichloroethylene (TCE) | 5 µg/L | 18 | 0 of 18 | not detected | 0 |
| Tetrachloroethylene (PCE) | 5 µg/L | 18 | 0 of 18 | not detected | 0 |
| Vinyl chloride | 2 µg/L | 18 | 0 of 18 | 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 of Columbus Public Water System.
Farm chemicals and metals
The water Gahanna City buys is treated by Columbus Public Water System, so the results below are Columbus Public Water System's.
EPA's file holds results for all nine herbicides and metals it checked. Detected: atrazine in 21 of 57 samples, highest 2.8 µg/L (limit 3); alachlor in 6 of 57 samples, highest 0.37 µg/L (limit 2); barium in 11 of 18 samples, highest 17 µg/L (limit 2,000). Not detected: 2,4-D in 2 samples, chromium in 18 samples, cadmium in 18 samples, mercury in 18 samples, selenium in 18 samples, thallium in 18 samples.
| Substance | Kind | Limit | Samples | Detected in | Highest result | Samples over limit |
|---|---|---|---|---|---|---|
| Atrazine | Farm chemical | 3 µg/L | 57 | 21 of 57 | 2.8 µg/L | 0 |
| Alachlor | Farm chemical | 2 µg/L | 57 | 6 of 57 | 0.37 µg/L | 0 |
| 2,4-D | Farm chemical | 70 µg/L | 2 | 0 of 2 | not detected | 0 |
| Chromium | Metal | 100 µg/L | 18 | 0 of 18 | not detected | 0 |
| Cadmium | Metal | 5 µg/L | 18 | 0 of 18 | not detected | 0 |
| Barium | Metal | 2,000 µg/L | 18 | 11 of 18 | 17 µg/L | 0 |
| Mercury | Metal | 2 µg/L | 18 | 0 of 18 | not detected | 0 |
| Selenium | Metal | 50 µg/L | 18 | 0 of 18 | not detected | 0 |
| Thallium | Metal | 2 µg/L | 18 | 0 of 18 | not detected | 0 |
Non-detects count as zero in the highest-result column.
EPA's file lumps the entry-point samples of all 3 plants of Columbus 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 of Columbus Public Water System.
Bacteria in the pipes
From 2012 to 2019, 2 of 4,224 routine total coliform samples taken in the distribution system at Gahanna City tested positive (0.05%); in 2019, the last year on file, 1 of 528 did. E. coli was never found in the 2 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 Gahanna City buys its water from Columbus Public Water System, a system that adjusts the fluoride level to the recommended level for preventing tooth decay.
EPA's treatment table lists fluoridation among the steps at Columbus Public Water System, which treats the water Gahanna City buys.
Measured fluoride: 0.97 mg/L on average leaving the plants of Columbus Public Water System, which supplies Gahanna City, in 2019 (in the range dentists aim for); samples ran from 0.82 to 1.01 mg/L across 18 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 Gahanna 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
The water Gahanna City buys is treated by Columbus Public Water System, so the results below are Columbus Public Water System's.
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 18 times in 802 raw-water samples, across 6 bloom seasons (2016 to 2026); the highest raw-water result was 0.7 µg/L on October 31, 2016. The highest raw-water result since 2024 was 0.29 µg/L.
In treated water, microcystin was detected 2 times; the highest result was 0.26 µg/L (October 2025), below the 0.3 µg/L advisory level.
In all, 1,604 samples from 2016 to 2026, the latest on August 24, 2026.
| Water | Samples | Detections | Highest result |
|---|---|---|---|
| Raw water, at the intake | 802 | 18 | 0.7 µg/L |
| Treated water | 802 | 2 | 0.26 µg/L |
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).
How well the service area is mapped
The service area drawn on the map for Gahanna City comes from the utility's own map.
Counting the people who live in the ZIP codes it overlaps, this atlas estimates 35,635 residents are inside the boundary, 107% of the 33,258 people Gahanna 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 OH2501303 (EPA ECHO).
Gahanna City's own pages: columbus.gov
