Water system
Montgomery County Water Services 2
EPA ID OH5701503 · Montgomery County · 83,033 people served · owned by a local government
Montgomery County Water Services 2 buys its water from Dayton Public Water System.
The system's record
- Aquifer
- Great Miami Buried Valley Aquifer
- Water bodies
- Great Miami River, Mad River
- Raw intakes
- Dayton Miami
Dayton Mad River - Active wells
- 105
- Serves
- 141,407 people · Montgomery County
- EPA ID
- OH5703512
Dayton draws groundwater via 105 wells in the Miami Wellfield and Mad River Wellfield (Great Miami Buried Valley Aquifer), which are recharged by and hydraulically connected to the Great Miami and Mad Rivers.
About this area's water
Did you know
- Firefighters let a Sherwin-Williams paint warehouse burn for six days in May 1987 rather than wash the runoff into the aquifer - the blaze sat almost on top of Dayton's Miami wellfield.
- Much of the county's water and sewer pipe is 80 to 105 years old; it logged 396 water main breaks in 2024 at a cost of $5.1 million.
- Replacing one mile of 8-inch water main now costs the county about $1.5 million, or $284 a foot - up 89% since 2016.
- Dayton's two plants are each rated 96 million gallons a day and pumped 23.92 billion gallons in 2024 from roughly 110 production wells.
History5
- 1985A Los Angeles Times front-page story exposed how close industrial pollution had come to Dayton's wells; the city had no chemical-spill policy and began drafting one.
- 1987In May a Sherwin-Williams paint warehouse burned beside the Miami wellfield; crews let it burn six days rather than wash chemicals into the shallow aquifer.
- 1988U.S. EPA designated the Great Miami Buried Valley Aquifer a sole source aquifer in May, and Dayton's commission passed its Source Water Protection Policy.
- 1995The source water protection policy was updated, and Dayton began an unbroken run as a Groundwater Foundation Groundwater Guardian Community.
- 2024Dayton's Ottawa plant reported PFOS averaging 9.5 ppt and PFHxS 13.1 ppt in finished water, above the PFAS limits EPA adopted that April.
Treatment & pressure
How it is treated
Dayton treats the water MCWS2 resells: conventional lime (calcium oxide) softening, pH adjustment with carbon dioxide, fluoridation, chlorine disinfection, then rapid sand filtration. The Miami and Ottawa plants are each rated 96 MGD and draw on ~110 wells.
Water pressure
not published - MCWS2 is a consecutive system reselling Dayton-treated water; no psi figure found. The county reports 11 water pumping stations and 14 storage facilities.
What it costs
$6.95 per 1,000 gallons
2026 county schedule: $50.96/1,000 cu ft residential plus $1.00 wellfield charge = ~$6.95/1,000 gal, plus $18.95 service and $7.45 capital per 91 days on a 5/8-in meter.
Water quality & impurities8
| Contaminant | Level | Limit | Year |
|---|---|---|---|
| Total trihalomethanes (TTHM) Highest running annual average; range 12.9-27.5 ppb across the two plants. | 28.3 ppb | 80 | 2024 |
| Haloacetic acids (HAA5) Highest running annual average; range 3.2-5.9 ppb. No violation. | 7.1 ppb | 60 | 2024 |
| Nitrate Ottawa plant high (range 0.62-1.51); Miami 1.20. Fertilizer runoff and septic leaching. | 1.51 ppm | 10 | 2024 |
| Turbidity Miami plant high; Ottawa 0.056. 100% of samples met the standard at both plants. | 0.088 NTU | TT: max 1 NTU… | 2024 |
| Lead (90th percentile) 0 of 54 samples over the action level; lead not detected in most samples. | <3.0 ppb | AL=15 | 2023 |
| Copper (90th percentile) 0 of 54 samples over the action level. | 0.044 ppm | AL=1.3 | 2023 |
| PFOS Ottawa plant average, range 5.51-15.45; above the new MCL. Miami plant <2.06 ppt. | 9.486 ppt | 4 (EPA MCL… | 2024 |
| PFHxS Ottawa plant average, range 6.70-17.18; above the new MCL. Miami plant <2.06 ppt. | 13.056 ppt | 10 (EPA MCL… | 2024 |
EPA compliance record
Lead at the tap: 90th-percentile result 0 ppb in 2025 (action level 15 ppb).
EPA health-based violations since 2015:
- 2017Lead and Copper Rule · treatment technique violation · returned to compliance
- 2016Lead and Copper Rule · treatment technique violation · returned to compliance
2 violations of any kind logged since 2020, 2 of them paperwork (monitoring, reporting, public notice or consumer report).
EPA compliance record · Dayton Public Water System (treats the water)
Lead at the tap: 90th-percentile result 0 ppb in 2023 (action level 15 ppb).
EPA record: no health-based violations since 2015.
Projects & plans3
Recent and current work
- Montgomery County water and sewer capital reinvestment · $208 million · 2018-2025 · completed
County reports over $208M invested since 2018, including $18.7M in grants and $17.2M in zero-interest loans. - 2024 water main break repairs · $5.1 million · 2024 · completed
396 breaks in 2024, a 123% increase in break count since 2016. Much of the buried system is 80-105 years old.
Planned or needed
- 5% annual water and sewer rate increases, 2026-2030 · 2026 · planned
County-adopted five-year schedule beginning Jan. 1, 2026 to fund over $248M of planned infrastructure; about $10.50 more per quarter at the start.
Supply stress
The Great Miami Buried Valley Aquifer stores ~1.5 trillion gallons and is drought resistant, but is shallow and, per Dayton's 2024 CCR, highly susceptible to surface contamination: thin clay cover and contaminant plumes in the wellfield protection area. Ottawa PFOS/PFHxS exceed 2024 federal MCLs.
Sewers
Sanitary
The county runs 2 water reclamation facilities, 1,237 miles of sewer main, 40 lift stations and 32,950 manholes, and also buys sewer treatment from Dayton - that cost rose 31% in five years. Plant names, capacities and any consent decree were not confirmed.
Storm
The county reports 2 stormwater lift stations and 3 equalization basins. Whether the collection system is combined or separate, and any stormwater fee, were not confirmed.
Sourcesverified
Compiled from the utility's own reports and public records, then independently re-checked against primary sources.
Main supplier in 4 ZIP codes
Serves
Main water supplier in 4 ZIP codes
- 45416 · Trotwood and Dayton100% of residents
- 45415 · Clayton and Dayton98% of residents
- 45414 · Harrison Township and Dayton73% of residents
- 45426 · Trotwood and Dayton62% of residents
Also present in 9 more ZIP codes
- 45405 · Dayton33% of residents
- 45315 · Clayton33% of residents
- 45417 · Dayton29% of residents
- 45322 · Englewood19% of residents
- 45406 · Dayton14% of residents
- 45424 · Huber Heights and Dayton8% of residents
- 45404 · Dayton5% of residents
- 45377 · Vandalia2% of residents
- 45309 · Brookville2% 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
Montgomery County Water Services 2 buys its water from Dayton Public Water System.
1 system on record buys water from Montgomery County Water Services 2: Oakwood Village MHP.
Photograph
On the map
Show this system's territory on the map — 13 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
Montgomery County Water Services 2's own pages: mcohio.org, mcohio.org, daytonohio.gov