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National Drinking Water Database


Total trihalomethanes (TTHMs) in Nevada


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

The Most Polluted Communities in Nevada

47 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)
1Nps Overton Beach
Boulder City, NV
2502 of 2137 ppb
(130 to 144 ppb)
2Nps Echo Bay
Boulder City, NV
2372 of 2112.5 ppb
(98 to 127 ppb)
3Las Vegas Valley Water District
Las Vegas, NV
1,181,2632 of 262 ppb
(62 ppb)
4Nps Callville Bay
Boulder City, NV
2503 of 348.13 ppb
(10.5 to 87.9 ppb)
5Mount Rose Bowl Homeowners Association
Reno, NV
401 of 141 ppb
(41 ppb)
6Truckee Meadows Water Authority
Reno, NV
315,2002 of 239.6 ppb
(39.6 ppb)
7City of Henderson
Boulder City, NV
246,0005 of 537.2 ppb
(31 to 44 ppb)
8Panther Valley Water Company
Reno, NV
1,8001 of 133.1 ppb
(33.1 ppb)
9City of North Las Vegas Utilities Department
N Las Vegas, NV
282,6002 of 332.67 ppb
(0 to 50 ppb)
10Storey County Water District
Virginia City, NV
6001 of 128 ppb
(28 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 Nevada

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

Violation TypeNumber of Violations
Monitoring and Reporting Disinfection Byproduct Rule58
Over maximum contaminant level, Average10