Drinking water quality, MT
Montana contaminants ranked by SDWA exceedance
Which regulated contaminants exceed their maximum contaminant level (MCL) most often across Montana's community water systems, per EPA's Six-Year Review sample-level dataset (2012-2019). Source data is public; every value is citable.
Top 15 contaminants by exceedance count
| Contaminant | Category | Samples | Above MCL | Munis affected |
|---|---|---|---|---|
| 1,1,2-trichloroethane | - | 3,223 | 0 | 243 |
| 1,1-dichloroethylene | - | 3,225 | 0 | 243 |
| 1,2,4-trichlorobenzene | - | 3,223 | 0 | 243 |
| 1,2-dibromo-3-chloropropane | - | 104 | 0 | 38 |
| 1,2-dichloroethane | - | 3,225 | 0 | 243 |
| 1,2-dichloropropane | - | 3,224 | 0 | 243 |
| 2,3,7,8-tcdd | - | 2 | 0 | 1 |
| 2,4,5-tp | - | 3,031 | 0 | 243 |
| 2,4-d | - | 3,032 | 0 | 243 |
| alachlor | - | 3,026 | 0 | 243 |
| antimony, total | inorganic | 2,360 | 0 | 233 |
| arsenic | inorganic | 3,503 | 0 | 242 |
| asbestos | - | 197 | 0 | 111 |
| atrazine | - | 3,034 | 0 | 243 |
| 1,1,1-trichloroethane | - | 3,222 | 0 | 243 |
For citizens
Look up your own water system by name on the muni search, then read the drinking-water quality band on its profile page for per-contaminant readings + MCL ratios.
For chemical suppliers
Contaminants near or above MCL signal treatment-chemical procurement pressure. Lane intelligence pairs this with per-chemical bid timing on the supplier tier.