The Power of Information

National Drinking Water Database


Total trihalomethanes (TTHMs) in New Hampshire


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

The Most Polluted Communities in New Hampshire

317 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)
1Swains Lake Village Water
Barrington, NH
1506 of 657.04 ppb
(<0.01 to 132 ppb)
2Cedar Wood Estates
Lee, NH
304 of 545.28 ppb
(0 to 116 ppb)
3Canaan Water Dept
Canaan, NH
6005 of 526.11 ppb
(<0.01 to 48.7 ppb)
4Keene Water Dept
Keene, NH
25,0005 of 624.19 ppb
(0 to 80.3 ppb)
5Pittsfield Aqueduct Co
Pittsfield, NH
1,5952 of 223 ppb
(<0.01 to 46 ppb)
6Reeds Crossing
Sandown, NH
404 of 421.05 ppb
(0.06 to 84 ppb)
7Ashley Commons
Milford, NH
753 of 320.34 ppb
(0.03 to 34 ppb)
8Lebanon Water Dept
Lebanon, NH
10,0504 of 419.38 ppb
(0.04 to 28.4 ppb)
9Bath Village Water Works
Bath, NH
952 of 216.05 ppb
(<0.01 to 32.1 ppb)
10Hanover Water Works Co
Hanover, NH
8,5001 of 113.6 ppb
(13.6 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 New Hampshire

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

Violation TypeNumber of Violations
Over maximum contaminant level, Average95
Monitoring and Reporting Disinfection Byproduct Rule29