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Tap water quality report

Unalaska, AK

EPA monitoring detected 17 contaminants across the 1 water supplier serving Unalaska. 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.

1
water supplier
9,400
people served
17
contaminants found
Alaska rankings Lead in Alaska PFAS in Alaska

What was found in Unalaska'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
Copper
1189 µg/L 91%
of the EPA limit 1300 µg/L
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2018
1/1 SYR4
Nitrate-Nitrite
140 µg/L 1.4%
of the EPA limit 10000 µg/L
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2019
1/1 SYR4
TTHM
40 µg/L 50%
of the EPA limit 80 µg/L
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2019
1/1 SYR4
Total Haloacetic Acids (HAA5)
36.295 µg/L 60%
of the EPA limit 60 µg/L
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2019
1/1 SYR4
Chloroform
28.61 µg/L
No EPA limit set
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2019
1/1 SYR4
Lead
24.4 µg/L 163%
of the EPA limit, at the 95th percentile of samples — 15 µg/L
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2018
1/1 SYR4
Trichloroacetic Acid
21.05 µg/L
No EPA limit set
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2019
1/1 SYR4
Monochloroacetic Acid
21 µg/L
No EPA limit set
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2019
1/1 SYR4
Dichloroacetic Acid
17 µg/L
No EPA limit set
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2019
1/1 SYR4
Bromodichloromethane
9.33 µg/L
No EPA limit set
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2019
1/1 SYR4
Barium
6.7 µg/L 0.3%
of the EPA limit 2000 µg/L
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2015
1/1 SYR4
Dibromochloromethane
3.509 µg/L
No EPA limit set
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2019
1/1 SYR4
Arsenic
2.575 µg/L 26%
of the EPA limit 10 µg/L
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2018
1/1 SYR4
Dibromoacetic Acid
1.275 µg/L
No EPA limit set
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2019
1/1 SYR4
Bromoform
0.5090 µg/L
No EPA limit set
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2019
1/1 SYR4
Combined Uranium
0.3486 µg/L 1.2%
of the EPA limit 30 µg/L
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2013
1/1 SYR4
Lead
0.0031 mg/L 20%
of the EPA limit 0.0150 mg/L
Main supplier: UNALASKA WATER SYSTEM · 9,400 people · 2024
1/1 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 Unalaska

SupplierPopulation served
UNALASKA WATER SYSTEM 9,400

Frequently asked questions about Unalaska tap water

Is Unalaska tap water safe to drink?

EPA testing detected 17 contaminants in the water serving Unalaska. 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 Unalaska?

1 public water supplier report drinking-water monitoring for Unalaska, Alaska to the EPA. Each is listed above with its population served.

What contaminants are in Unalaska's water?

The contaminants EPA monitoring detected in Unalaska include Copper, Nitrate-Nitrite, TTHM, Total Haloacetic Acids (HAA5), Chloroform. 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.