What was found in Mount Vernon's water
The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Nitrate | 1540 µg/L 15% of the EPA limit 10000 µg/L Highest in the city: KNOX COUNTY WATER AND WASTEWATER PWS · 7,710 people · 2019 | 3/4 | SYR4 |
| Nitrate-Nitrite | 1524 µg/L 15% of the EPA limit 10000 µg/L Highest in the city: KNOX COUNTY WATER AND WASTEWATER PWS · 7,710 people · 2019 | 3/4 | SYR4 |
| Fluoride | 339.9 µg/L 8.5% of the EPA limit 4000 µg/L Main supplier: MOUNT VERNON CITY PWS · 16,990 people · 2018
Highest in the city: 1042 µg/L — KNOX COUNTY WATER AND WASTEWATER PWS · 7,710 people · 2018 | 4/4 | SYR4 |
| Copper | 40.75 µg/L 3.1% of the EPA limit 1300 µg/L Main supplier: MOUNT VERNON CITY PWS · 16,990 people · 2019
Highest in the city: 893.2 µg/L — KNOX COUNTY WATER AND WASTEWATER PWS · 7,710 people · 2019 | 4/4 | SYR4 |
| Chlorite | 480.5 µg/L 48% of the EPA limit 1000 µg/L Main supplier: MOUNT VERNON CITY PWS · 16,990 people · 2019 | 1/4 | SYR4 |
| Barium | 20.9 µg/L 1% of the EPA limit 2000 µg/L Main supplier: MOUNT VERNON CITY PWS · 16,990 people · 2018
Highest in the city: 64 µg/L — GRANDVIEW MHP A PWS · 74 people · 2018 | 3/4 | SYR4 |
| Lead | 18.91 µg/L 126% of the EPA limit, at the 95th percentile of samples — 15 µg/L Main supplier: MOUNT VERNON CITY PWS · 16,990 people · 2019
Highest in the city: 54.075 µg/L — KNOX COUNTY WATER AND WASTEWATER PWS · 7,710 people · 2019 | 3/4 | SYR4 |
| TTHM | 51.95 µg/L 65% of the EPA limit 80 µg/L Highest in the city: GRANDVIEW MHP B · 47 people · 2019 | 3/4 | SYR4 |
| Total Haloacetic Acids (HAA5) | 50.21 µg/L 84% of the EPA limit 60 µg/L Highest in the city: GRANDVIEW MHP B · 47 people · 2019 | 3/4 | SYR4 |
| Dichloroacetic Acid | 38.58 µg/L No EPA limit set Highest in the city: GRANDVIEW MHP B · 47 people · 2019 | 3/4 | SYR4 |
| Chloroform | 25.675 µg/L No EPA limit set Highest in the city: GRANDVIEW MHP B · 47 people · 2019 | 3/4 | SYR4 |
| Bromodichloromethane | 20 µg/L No EPA limit set Highest in the city: GRANDVIEW MHP B · 47 people · 2019 | 3/4 | SYR4 |
| Trichloroacetic Acid | 8.8215 µg/L No EPA limit set Highest in the city: GRANDVIEW MHP B · 47 people · 2019 | 3/4 | SYR4 |
| Dibromochloromethane | 7.725 µg/L No EPA limit set Highest in the city: KNOX COUNTY WATER AND WASTEWATER PWS · 7,710 people · 2019 | 3/4 | SYR4 |
| Monochloroacetic Acid | 7.715 µg/L No EPA limit set Highest in the city: GRANDVIEW MHP A PWS · 74 people · 2019 | 2/4 | SYR4 |
| Monobromoacetic Acid | 5.7 µg/L No EPA limit set Highest in the city: GRANDVIEW MHP B · 47 people · 2019 | 1/4 | SYR4 |
| Toluene | 5.7 µg/L 0.6% of the EPA limit 1000 µg/L Highest in the city: GRANDVIEW MHP A PWS · 74 people · 2018 | 1/4 | SYR4 |
| Arsenic | 4.5 µg/L 45% of the EPA limit 10 µg/L Highest in the city: GRANDVIEW MHP B · 47 people · 2018 | 2/4 | SYR4 |
| Dibromoacetic Acid | 3.709 µg/L No EPA limit set Highest in the city: GRANDVIEW MHP B · 47 people · 2019 | 3/4 | SYR4 |
| Bromoform | 2.898 µg/L No EPA limit set Highest in the city: GRANDVIEW MHP A PWS · 74 people · 2019 | 3/4 | SYR4 |
| Combined Radium (-226 And -228) | 1.03 pCi/L 21% of the EPA limit 5 pCi/L Highest in the city: GRANDVIEW MHP B · 47 people · 2015 | 1/4 | SYR4 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: MOUNT VERNON CITY PWS · 16,990 people · 2025
Highest in the city: 0.0021 mg/L — KNOX COUNTY WATER AND WASTEWATER PWS · 7,710 people · 2025 | 4/4 | LCR |
Each bar shows the measured level as a share of the EPA limit: green is
well under, amber is close to it, red is over. For lead and copper the
limit applies to exactly the 90th-percentile figure shown, so red there
means a real exceedance. For everything else the limit applies to a
running annual average while the figure is the 95th percentile of the
system's samples — over 100% is worth reading, but is not by itself a
violation.
Formal violations are listed separately.
These are the utilities' own EPA-reported results, not a city-wide
average. A detection means the lab measured the
substance — it isn't the same as exceeding a legal limit. Hover a source
tag to see the EPA program and years behind each figure.
Water suppliers serving Mount Vernon
| Supplier | Population served |
|---|---|
| MOUNT VERNON CITY PWS | 16,990 |
| KNOX COUNTY WATER AND WASTEWATER PWS | 7,710 |
| GRANDVIEW MHP A PWS | 74 |
| GRANDVIEW MHP B | 47 |
Frequently asked questions about Mount Vernon tap water
Is Mount Vernon tap water safe to drink?
EPA testing detected 22 contaminants in the water serving Mount Vernon. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.
How many water suppliers serve Mount Vernon?
4 public water suppliers report drinking-water monitoring for Mount Vernon, Ohio to the EPA. Each is listed above with its population served.
What contaminants are in Mount Vernon's water?
The contaminants EPA monitoring detected in Mount Vernon include Nitrate, Nitrate-Nitrite, Fluoride, Copper, Chlorite. The full list, with the level at the main supplier and the data source, is in the table above.
Where does this data come from?
Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.