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Tap water quality report

Darby, MT

EPA monitoring detected 15 contaminants across the 2 water suppliers serving Darby. A detection doesn't automatically mean the water is unsafe — see the level at the main supplier for each below, with its EPA source and period.

2
water suppliers
1,125
people served
15
contaminants found
Montana rankings Lead in Montana PFAS in Montana

What was found in Darby'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.

ContaminantLevel vs EPA limitSuppliersSource
Nitrate-Nitrite
1720 µg/L 17%
of the EPA limit 10000 µg/L
Main supplier: DARBY TOWN OF · 850 people · 2019
2/2 SYR4
Copper
1226.5 µg/L 94%
of the EPA limit 1300 µg/L
Main supplier: DARBY TOWN OF · 850 people · 2018
1/2 SYR4
Fluoride
600 µg/L 15%
of the EPA limit 4000 µg/L
Main supplier: DARBY TOWN OF · 850 people · 2012
2/2 SYR4
Lead
5.75 µg/L 38%
of the EPA limit 15 µg/L
Main supplier: DARBY TOWN OF · 850 people · 2018
1/2 SYR4
Combined Radium (-226 And -228)
3.5 pCi/L 70%
of the EPA limit 5 pCi/L
Highest in the city: TRAPPER CREEK JOB CORPS · 275 people · 2017
1/2 SYR4
TTHM
2.07 µg/L 2.6%
of the EPA limit 80 µg/L
Main supplier: DARBY TOWN OF · 850 people · 2019
Highest in the city: 2.19 µg/L — TRAPPER CREEK JOB CORPS · 275 people · 2019
2/2 SYR4
Gross Alpha, Excl. Radon And U
2 pCi/L 13%
of the EPA limit 15 pCi/L
Main supplier: DARBY TOWN OF · 850 people · 2019
2/2 SYR4
Total Haloacetic Acids (HAA5)
1.39 µg/L 2.3%
of the EPA limit 60 µg/L
Main supplier: DARBY TOWN OF · 850 people · 2019
2/2 SYR4
Dichloroacetic Acid
0.9190 µg/L
No EPA limit set
Main supplier: DARBY TOWN OF · 850 people · 2019
Highest in the city: 1.1 µg/L — TRAPPER CREEK JOB CORPS · 275 people · 2019
2/2 SYR4
Chloroform
0.9200 µg/L
No EPA limit set
Main supplier: DARBY TOWN OF · 850 people · 2019
2/2 SYR4
Bromodichloromethane
0.8480 µg/L
No EPA limit set
Main supplier: DARBY TOWN OF · 850 people · 2019
2/2 SYR4
Dibromochloromethane
0.5880 µg/L
No EPA limit set
Highest in the city: TRAPPER CREEK JOB CORPS · 275 people · 2019
1/2 SYR4
Trichloroacetic Acid
0.5600 µg/L
No EPA limit set
Main supplier: DARBY TOWN OF · 850 people · 2019
1/2 SYR4
Dibromoacetic Acid
0.3375 µg/L
No EPA limit set
Highest in the city: TRAPPER CREEK JOB CORPS · 275 people · 2019
1/2 SYR4
Lead
0.0 mg/L 0%
of the EPA limit 0.0150 mg/L
Main supplier: DARBY TOWN OF · 850 people · 2025
Highest in the city: 0.0060 mg/L — TRAPPER CREEK JOB CORPS · 275 people · 2023
2/2 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 Darby

SupplierPopulation served
DARBY TOWN OF 850
TRAPPER CREEK JOB CORPS 275

Frequently asked questions about Darby tap water

Is Darby tap water safe to drink?

EPA testing detected 15 contaminants in the water serving Darby. 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 Darby?

2 public water suppliers report drinking-water monitoring for Darby, Montana to the EPA. Each is listed above with its population served.

What contaminants are in Darby's water?

The contaminants EPA monitoring detected in Darby include Nitrate-Nitrite, Copper, Fluoride, Lead, Combined Radium (-226 And -228). 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.