Water system
Del-co Water Company, Inc.
EPA ID OH2101412 · Delaware County · 150,000 people served
Del-co Water Company, Inc. treats its own water from Olentangy River, O'Shaughnessy and Alum Creek reservoirs, plus Knox County wells.
The system's record
- Aquifer
- Sand-and-gravel aquifer, Knox County well field
- Water bodies
- Olentangy River, O'Shaughnessy Reservoir (Scioto River), Alum Creek Reservoir
- Raw intakes
- Del Co Olentangy River
Olentangy Reservoir
Del Co McNamara Reservoir
Del Co Alum Creek Reservoir
Del Co O'Shaughnessy Reservoir Scioto - Active wells
- 4
- Serves
- 150,000 people · Delaware County
- EPA ID
- OH2101412
About this area's water
Did you know
- Del-Co is a member-owned nonprofit 501(c)(12) cooperative, not a city department, licensed by Ohio EPA to run four plants and thirty elevated tanks across eight central Ohio counties.
- Its six above-ground reservoirs hold more than 2.6 billion gallons of raw water, banked during high stream flows for use when the rivers run low.
- Nearly all of it comes from one basin: the Olentangy River, O'Shaughnessy Reservoir and Alum Creek Reservoir all sit in the Upper Scioto watershed, with Knox County wells the lone exception.
- Treatment starts with potassium permanganate dosed into the raw water for one specific reason: killing zebra mussels before they reach the plant.
History5
- 1969Del-Co Water Company founded by Ralph Scott, Timothy McNamara and Gerald Solt, financed through the USDA Farmers Home Administration.
- 1969Original system: a 1-million-gallon-per-day treatment plant, 200 miles of underground pipe and a single elevated tank.
- 2001In October 2001 Ohio EPA approved Del-Co's Wellhead/Drinking Water Source Protection Plan for the Knox County well field.
- 2025Effective May 1, 2025 Del-Co scrapped minimum allowances and dropped its conservation tier from 25,000 to 10,000 gallons a month.
- 2026Effective May 1, 2026 rates rose again: $5.00, $8.50 and $12.00 per 1,000 gallons across three tiers, base fee up $1 to $15.00.
Treatment & pressure
How it is treated
Raw water gets potassium permanganate for zebra mussel control, then ferric chloride and lime in a flash mixer, settling, carbon dioxide stabilization, filtration through fine coal and silicate sand, chlorine, fluoride, and phosphate for corrosion control.
Water pressure
Published: Del-Co says it has historically delivered 40-100 psi, per the Recommended Standards for Water Works. Roughly thirty elevated tanks span eight counties.
What it costs
$5.00 per 1,000 gallons
Typical household bill about $48 a month for water.
Effective May 1, 2026: $5.00/1,000 gal to 4,000; $8.50 to 10,000; $12.00 above; plus a $15.00 monthly base for a 5/8-inch meter. Residential.
Water quality & impurities7
| Contaminant | Level | Limit | Year |
|---|---|---|---|
| Total trihalomethanes (TTHM) Reported at 79.95 against an 80 ppb MCL; no violation. Sample range 24.8-75.3 ppb. | 79.95 ppb | 80 | 2025 |
| Haloacetic acids (HAA5) Disinfection byproduct; range 10.1-45.0 ppb, well under the limit. | 38.78 ppb | 60 | 2025 |
| Lead (90th percentile) 0 of 50 sites above the action level; range 0.26-3.15 ppb. Replaces a stale 2018 figure. | 0.85 ppb | 15 | 2024 |
| Copper (90th percentile) 0 of 50 sites above the action level; range 0.01-0.35 ppm. | 0.22 ppm | 1.3 | 2024 |
| Nitrate Farm runoff indicator; range 0.21-1.4 ppm, far below the limit. | 1.4 ppm | 10 | 2025 |
| Atrazine Row-crop herbicide runoff; range 0.31-0.76 ppb. | 0.47 ppb | 3 | 2025 |
| PFAS Ohio EPA sampled the Olentangy, Alum Creek and Knox plants; no detections. | ND ppt | 4 (PFOA/PFOS… | 2020 |
EPA compliance record
Lead at the tap: 90th-percentile result 0.8 ppb in 2024 (action level 15 ppb).
EPA record: no health-based violations since 2015.
Supply stress
Del-Co calls its Olentangy River, O'Shaughnessy and Alum Creek sources highly susceptible to contamination from farm runoff, septics and road and rail crossings, and its Knox County wellfield relatively so. Output averages near 13 MGD against 45 MGD design capacity in fast-growing Delaware County.
Sewers
Sanitary
Del-Co is a drinking-water-only cooperative and provides no sanitary sewer service. Sewers in its territory are run by local municipalities, townships or county sewer districts.
Storm
Not applicable. Del-Co operates no storm sewers; stormwater is handled by the townships and municipalities across its eight-county service area.
Sourcesverified
Compiled from the utility's own reports and public records, then independently re-checked against primary sources.
Main supplier in 19 ZIP codes
Serves
Main water supplier in 20 ZIP codes
- 43021 · Genoa Township and Galena100% of residents
- 43032 · Brown Township and Kilbourne100% of residents
- 43317 · Chesterville100% of residents
- 43320 · Canaan Township and Edison100% of residents
- 43321 · Fulton100% of residents
- 43325 · Washington Township and Iberia100% of residents
- 43334 · Bennington Township and Marengo100% of residents
- 43350 · Sparta100% of residents
- 43074 · Sunbury99% of residents
- 43065 · Powell84% of residents
- 43035 · Orange Township and Lewis Center80% of residents
- 43061 · Scioto Township and Ostrander79% of residents
- 43315 · Cardington73% of residents
- 43314 · Claridon Township and Caledonia72% of residents
- 43011 · Hilliar Township and Centerburg72% of residents
- 43082 · Genoa Township and Westerville71% of residents
- 43066 · Radnor Township and Radnor66% of residents
- 43356 · Waldo Township and Waldo65% of residents
- 43003 · Ashley53% of residents
- 43013 · Hartford Township and Croton2% of residents
Also present in 12 more ZIP codes
- 43015 · Delaware37% of residents
- 43338 · Mount Gilead24% of residents
- 43019 · Fredericktown10% of residents
- 44833 · Galion9% of residents
- 43017 · Dublin6% of residents
- 43031 · Johnstown3% of residents
- 43302 · Marion3% of residents
- 43081 · Westerville1% of residents
- 43064 · Jerome Township and Plain City1% of residents
- 43016 · Columbus and Dublin1% of residents
- 43054 · Columbus and New Albany0% of residents
- 43040 · Marysville0% 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
Del-co Water Company, Inc. does not buy water from another system on record; it treats its own source water.
1 system on record buys water from Del-co Water Company, Inc.: Ashley Village.
What the records show about Del-co Water Company, Inc.
Who runs it
EPA's record says Del-co Water Company, Inc. has 56,000 service connections and serves 150,000 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 740-201-0125.
Source: EPA Safe Drinking Water Information System (SDWIS), water system record.
How the water is treated
EPA's treatment table registers these steps for Del-co Water Company, Inc.: corrosion control, coagulation and settling, chlorine disinfection, iron and manganese removal, fluoridation, 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 Del-co Water Company, Inc. since 2015.
EPA logs no violations of any kind for Del-co Water Company, Inc. 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 December 2024, the 90th-percentile lead result at Del-co Water Company, Inc. was 0.8 ppb, under both the current 15 ppb action level and the 10 ppb level that applies from 2027.
The highest result on file is 5.9 ppb, in the period ending December 2018.
EPA has 3 sampling periods on file for Del-co Water Company, Inc. 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 Del-co Water Company, Inc. sent EPA, 56,197 lines are counted.
| Material | Lines |
|---|---|
| Lead | 9 |
| Galvanized, needing replacement | 19 |
| Unknown material | 14,186 |
| Not lead | 41,983 |
| All lines | 56,197 |
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 11 samples of the water entering the pipes of Del-co Water Company, Inc. in 2023 to 2024 and measured 29 PFAS.
The highest PFOA or PFOS result, 4.2 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 PFBA 10.7 ng/L, PFHxA 8.7 ng/L, and PFPeA 6.3 ng/L.
The highest PFOA or PFOS result was measured at Olentangy WTP.
Ohio EPA's own statewide sampling tested 3 plants of Del-co Water Company, Inc. (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 3 plants of Del-co Water Company, Inc. as sampled, most recently April 2024.
| Compound | Highest result | Federal limit |
|---|---|---|
| PFOA | 4.2 ng/L | 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 Del-co Water Company, Inc.'s samples in 2019, the last year it was sampled, was 55.9 µg/L. The worst yearly average was 60.9 µg/L and the highest single sample was 95.7 µg/L, from 256 samples taken from 2012 to 2019.
For HAA5, the average in the last year sampled was 35.8 µg/L. The worst yearly average was 37.8 µg/L and the highest single sample was 58 µg/L, from 256 samples.
| Byproduct | Limit | Latest yearly average | Worst yearly average | Highest sample | Samples |
|---|---|---|---|---|---|
| TTHM | 80 µg/L | 55.9 µg/L (2019) | 60.9 µg/L | 95.7 µg/L | 256 |
| HAA5 | 60 µg/L | 35.8 µg/L | 37.8 µg/L | 58 µg/L | 256 |
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 225 samples was 2.3 mg/L (as nitrogen) in 2015; in 2019, the last year sampled, the highest was 1.86 mg/L. No sample was over the limit of 10 mg/L. Nitrate above 10 is unsafe for infants.
Arsenic was not detected in 31 samples (limit 10 µg/L).
| Contaminant | Samples | Highest result | Limit | Samples over limit |
|---|---|---|---|---|
| Nitrate (as nitrogen) | 225 | 2.3 mg/L | 10 mg/L | 0 |
| Arsenic | 31 | 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 4 plants of Del-co Water Company, Inc. 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 28 samples each.
| Compound | Limit | Samples | Detected in | Highest result | Samples over limit |
|---|---|---|---|---|---|
| Benzene | 5 µg/L | 28 | 0 of 28 | not detected | 0 |
| Carbon tetrachloride | 5 µg/L | 28 | 0 of 28 | not detected | 0 |
| 1,2-dichloroethane | 5 µg/L | 28 | 0 of 28 | not detected | 0 |
| Trichloroethylene (TCE) | 5 µg/L | 28 | 0 of 28 | not detected | 0 |
| Tetrachloroethylene (PCE) | 5 µg/L | 28 | 0 of 28 | not detected | 0 |
| Vinyl chloride | 2 µg/L | 28 | 0 of 28 | 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 55 of 57 samples, highest 1.55 µg/L (limit 3); alachlor in 1 of 57 samples, highest 0.6 µg/L (limit 2); barium in 23 of 31 samples, highest 34 µg/L (limit 2,000). Not detected: chromium, cadmium, mercury, selenium, and thallium, in 31 samples each.
| Substance | Kind | Limit | Samples | Detected in | Highest result | Samples over limit |
|---|---|---|---|---|---|---|
| Atrazine | Farm chemical | 3 µg/L | 57 | 55 of 57 | 1.55 µg/L | 0 |
| Alachlor | Farm chemical | 2 µg/L | 57 | 1 of 57 | 0.6 µg/L | 0 |
| Chromium | Metal | 100 µg/L | 31 | 0 of 31 | not detected | 0 |
| Cadmium | Metal | 5 µg/L | 31 | 0 of 31 | not detected | 0 |
| Barium | Metal | 2,000 µg/L | 31 | 23 of 31 | 34 µg/L | 0 |
| Mercury | Metal | 2 µg/L | 31 | 0 of 31 | not detected | 0 |
| Selenium | Metal | 50 µg/L | 31 | 0 of 31 | not detected | 0 |
| Thallium | Metal | 2 µg/L | 31 | 0 of 31 | not detected | 0 |
Non-detects count as zero in the highest-result column.
EPA's file lumps the entry-point samples of all 4 plants of Del-co Water Company, Inc. 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, 1 of 11,459 routine total coliform samples taken in the distribution system at Del-co Water Company, Inc. tested positive (0.01%); in 2019, the last year on file, 1 of 1,440 did. E. coli was found in 1 of 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 Del-co Water Company, Inc. adjusts the fluoride level to the recommended level for preventing tooth decay.
EPA's treatment table lists fluoridation among the steps at Del-co Water Company, Inc.
Measured fluoride: 1.04 mg/L on average at the plant's entry points in 2019 (in the range dentists aim for); samples ran from 0.68 to 1.2 mg/L across 31 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 found in 2 of 10 UCMR 5 samples at Del-co Water Company, Inc., highest 12.9 µg/L; detections averaged 12.6, last sampled in 2024.
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.
No microcystin was detected in the 466 raw-water samples.
Microcystin was never detected in treated water (165 samples).
In all, 631 samples from 2016 to 2026, the latest on August 24, 2026.
| Water | Samples | Detections | Highest result |
|---|---|---|---|
| Raw water, at the intake | 466 | 0 | not detected |
| Treated water | 165 | 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 Del-co Water Company, Inc. for a household using 5,000 gallons a month at $469 a year, about $39 a month.
| Use | Water, per year | Sewer, per year |
|---|---|---|
| 2,500 gallons a month | $252 | not on file |
| 5,000 gallons a month | $469 | not on file |
| 8,000 gallons a month | $714 | not on file |
The survey lists it as “Del-Co Water”. 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 Del-co Water Company, Inc. comes from the utility's own map.
Counting the people who live in the ZIP codes it overlaps, this atlas estimates 177,671 residents are inside the boundary, 118% of the 150,000 people Del-co Water Company, Inc. 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 — 32 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 OH2101412 (EPA ECHO).
Del-co Water Company, Inc.'s own pages: delcowater.org, delcowater.org
