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National Drinking Water Database


Total trihalomethanes (TTHMs) in Pennsylvania


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

The Most Polluted Communities in Pennsylvania

1,663 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)
1South Pymatuning
Sharpsville, PA
1,00015 of 15106.01 ppb
(51.3 to 190 ppb)
2Sharpsville Boro Water Co
Sharpsville, PA
4,72921 of 2187.54 ppb
(37 to 160 ppb)
3South Buffalo Twp Muni Auth
Freeport, PA
82521 of 2187.3 ppb
(42 to 164.8 ppb)
4West Bethlehem Twp Water Dist
Marianna, PA
43015 of 1587.19 ppb
(31 to 160 ppb)
5Marion Twp Water Sys
Fombell, PA
22015 of 1583.99 ppb
(44.91 to 120 ppb)
6Blacklick Valley Muni Auth
Twin Rocks, PA
2,04022 of 2283.74 ppb
(42.45 to 153.1 ppb)
7West Alexander Muni Auth
West Alexander, PA
97521 of 2181.19 ppb
(18.3 to 155 ppb)
8West Manheim Water Auth
Hanover, PA
4,48722 of 2279.38 ppb
(42.2 to 135.9 ppb)
9Ohioville Boro Muni Auth
Industry, PA
2,63022 of 2278.23 ppb
(34 to 144.5 ppb)
10Cokeburg Boro Water Dept
Cokeburg, PA
72020 of 2178.13 ppb
(0 to 171.7 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 Pennsylvania

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

Violation TypeNumber of Violations
Monitoring and Reporting Disinfection Byproduct Rule809
Over maximum contaminant level, Average158