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National Drinking Water Database


Total trihalomethanes (TTHMs) in Alaska


Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform. [read more]

The Most Polluted Communities in Alaska

199 water utilities reported detecting Total trihalomethanes (TTHMs) in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies

Ranked by highest average Total trihalomethanes (TTHMs) level

RankSystem Population Served Positive test results of total reported tests Average Level
(Range)
1Golovin Community Water System
Golovin, AK
1503 of 3178.33 ppb
(150 to 213 ppb)
2Gulkana Village
Gakona, AK
8313 of 13165.97 ppb
(37.6 to 216 ppb)
3Selawik Safewater Facility
Selawik, AK
8008 of 8150.59 ppb
(103 to 201 ppb)
4Thorne Bay
Thorne Bay, AK
95715 of 15149.95 ppb
(66.5 to 230 ppb)
5Shishmaref Water System
Shishmaref, AK
57213 of 13136.48 ppb
(64.2 to 205 ppb)
6Saxman
Ketchikan, AK
45019 of 19133.36 ppb
(57 to 226 ppb)
7Kasaan
Ketchikan, AK
4613 of 13116.78 ppb
(27.8 to 237 ppb)
8Newtok Water System
Newtok, AK
2151 of 1109 ppb
(109 ppb)
9Nunam Iqua
Nunam Iqua, AK
21313 of 1397.6 ppb
(44 to 173 ppb)
10Shaktoolik Water System
Shaktoolik, AK
2404 of 496.5 ppb
(35.4 to 211 ppb)

Health Based Limits for Total trihalomethanes (TTHMs)

StandardDescriptionLevel
One in one million (10-6) Cancer RiskThe concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 1,000,000. Source: U.S. Environmental Protection Agency.9.8 ppb
EPA Human Health Water Quality CriteriaWater quality criteria set by the US EPA provide guidance for states and tribes authorized to establish water quality standards under the Clean Water Act (CWA) to protect human health. These are non-enforceable standards based upon exposure by both drinking water and the contribution of water contamination to other consumed foods. Source: U.S. Environmental Protection Agency.11.5 ppb
Maximum Contaminant Limit (MCL)The enforceable standard which defines the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to health-based limits (Maximum Contaminant Level Goals, or MCLGs) as feasible using the best available analytical and treatment technologies and taking cost into consideration. Source: U.S. Environmental Protection Agency.80 ppb
Lifetime health-based limit, non-cancer riskConcentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic health effects for a lifetime of exposure. The Lifetime health-based limit (or Health Advisory, HA) is based on exposure for a a 70-kg adult consuming 2 liters of water per day. Source: U.S. Environmental Protection Agency.130 ppb
One in ten thousand (10-4) Cancer RiskThe concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 10,000. Source: U.S. Environmental Protection Agency.980 ppb
Drinking Water Equivalent LevelA lifetime exposure concentration protective of adverse, noncarcinogenic health effects, that assumes all of the exposure to a contaminant is from drinking water. Source: U.S. Environmental Protection Agency.1835 ppb
Children's health-based limit for 10-day exposureConcentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic effects for up to ten days of exposure. The Ten-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.4860 ppb
Children's health-based limit for 1-day exposureConcentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic health effects for up to one day of exposure. The One-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.10600 ppb

Violation Summary for Total trihalomethanes (TTHMs) in Alaska

Data from the U.S. Environmental Protection Agency includes the following violations of federal standards in Alaska since 2004

Violation TypeNumber of Violations
Monitoring and Reporting Disinfection Byproduct Rule392
Over maximum contaminant level, Average208
Over maximum contaminant level, Single Sample36