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National Drinking Water Database


Total trihalomethanes (TTHMs) in Arizona


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

The Most Polluted Communities in Arizona

286 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)
1Mohawk Utility Co
Wellton, AZ
2501 of 179.7 ppb
(79.7 ppb)
2Ehrenberg Improvement Assn
Ehrenberg, AZ
1,6501 of 178 ppb
(78 ppb)
3Eloy Detention Center
Eloy, AZ
1,6002 of 268 ppb
(53 to 83 ppb)
4Katherine Resorts Landing
San Diego, AZ
781 of 158.5 ppb
(58.5 ppb)
5Far West Water Co
Yuma, AZ
32,42536 of 3755.91 ppb
(0 to 109 ppb)
6AZ American Water - Camp Mohave
Phoenix, AZ
1684 of 553.05 ppb
(0 to 80.7 ppb)
7Cameron Trading Post
Cameron, AZ
8504 of 650.67 ppb
(0 to 130 ppb)
8Usmc-Air Station-Main
Yuma, AZ
6,32416 of 2250.16 ppb
(0 to 153.33 ppb)
9Marina Village
Bakersfield, AZ
5542 of 447.25 ppb
(0 to 130 ppb)
10Town of Kearny
Kearny, AZ
2,2491 of 144 ppb
(44 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 Arizona

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

Violation TypeNumber of Violations
Monitoring and Reporting Disinfection Byproduct Rule1,004
Over maximum contaminant level, Average30