What was found in Great Falls's water
The highest level seen across the city's suppliers, the EPA limit for each, and where the figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Nitrate-Nitrite | 4100 µg/L 41% of the EPA limit 10000 µg/L | 10/27 | SYR4 |
| Fluoride | 3200 µg/L 80% of the EPA limit 4000 µg/L | 10/27 | SYR4 |
| Copper | 2510 µg/L 193% of the EPA limit, in the worst sample — 1300 µg/L | 13/27 | SYR4 |
| Total Haloacetic Acids (HAA5) | 109 µg/L 182% of the EPA limit, in the worst sample — 60 µg/L | 7/27 | SYR4 |
| TTHM | 104 µg/L 130% of the EPA limit, in the worst sample — 80 µg/L | 8/27 | SYR4 |
| Chloroform | 93 µg/L No EPA limit set | 4/27 | SYR4 |
| Lithium | 80.8 µg/L No EPA limit set | 2/27 | UCMR-5 |
| Trichloroacetic Acid | 61 µg/L No EPA limit set | 4/27 | SYR4 |
| Barium | 50 µg/L 2.5% of the EPA limit 2000 µg/L | 2/27 | SYR4 |
| Dichloroacetic Acid | 48 µg/L No EPA limit set | 4/27 | SYR4 |
| Gross Alpha, Excl. Radon And U | 34 pCi/L 227% of the EPA limit, in the worst sample — 15 pCi/L | 7/27 | SYR4 |
| Arsenic | 33 µg/L 330% of the EPA limit, in the worst sample — 10 µg/L | 7/27 | SYR4 |
| Lead | 24 µg/L 160% of the EPA limit, in the worst sample — 15 µg/L | 11/27 | SYR4 |
| Selenium | 20 µg/L 40% of the EPA limit 50 µg/L | 7/27 | SYR4 |
| Combined Uranium | 19 µg/L 63% of the EPA limit 30 µg/L | 8/27 | SYR4 |
| Bromodichloromethane | 16 µg/L No EPA limit set | 5/27 | SYR4 |
| Dibromochloromethane | 14 µg/L No EPA limit set | 5/27 | SYR4 |
| Bromoform | 13 µg/L No EPA limit set | 6/27 | SYR4 |
| Gross Beta Particle Activity | 11 pCi/L No EPA limit set | 1/27 | SYR4 |
| Chromium | 9 µg/L 9% of the EPA limit 100 µg/L | 1/27 | SYR4 |
| Dibromoacetic Acid | 7 µg/L No EPA limit set | 7/27 | SYR4 |
| Combined Radium (-226 And -228) | 4.8 pCi/L 96% of the EPA limit 5 pCi/L | 7/27 | SYR4 |
| Monochloroacetic Acid | 4 µg/L No EPA limit set | 2/27 | SYR4 |
| Monobromoacetic Acid | 1.8 µg/L No EPA limit set | 3/27 | SYR4 |
| Hexachlorocyclopentadiene | 0.1200 µg/L 0.2% of the EPA limit 50 µg/L | 1/27 | SYR4 |
| Lead | 0.0120 mg/L 80% of the EPA limit 0.0150 mg/L | 19/27 | LCR |
| Pfba | 0.0070 µg/L No EPA limit set | 1/27 | UCMR-5 |
Water suppliers serving Great Falls
Frequently asked questions about Great Falls tap water
Is Great Falls tap water safe to drink?
EPA testing detected 27 contaminants in the water serving Great Falls. 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 Great Falls?
27 public water suppliers report drinking-water monitoring for Great Falls, Montana to the EPA. Each is listed above with its population served.
What contaminants are in Great Falls's water?
The contaminants EPA monitoring detected in Great Falls include Nitrate-Nitrite, Fluoride, Copper, Total Haloacetic Acids (HAA5), TTHM. The full list, with the highest level found 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.