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EWG's Tap Water Database — 2021 UPDATE

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Total trihalomethanes (TTHMs)

City of Bogalusa Water System

Trihalomethanes are cancer-causing contaminants that form during water treatment with chlorine and other disinfectants. The total trihalomethanes group includes four chemicals: chloroform, bromodichloromethane, dibromochloromethane and bromoform. Read More.

Studies conducted in the U.S. and Europe have found that drinking tap water that carries disinfection byproducts increases the risk of developing bladder cancer. In animal studies, all trihalomethanes cause liver, kidney and intestinal tumors. Some human epidemiological studies also reported an association between disinfection byproducts and an increased risk of problems during pregnancy, including spontaneous miscarriage, cardiovascular defects, neural tube defects and low birth weight.

The health guideline of 0.15 parts per billion, or ppb, for the group of four trihalomethanes, or THM4/TTHM, was defined in a peer-reviewed scientific study by EWG and represents a one-in-one-million lifetime cancer risk level.

Click here to read more about disinfection byproducts.

MORE ABOUT THIS CONTAMINANT

 

192

Samples

0

Samples exceeding legal limit (MCL)

158

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20142.73 ppb3226ND - 8.00 ppb
20153.39 ppb3228ND - 14.1 ppb
20161.67 ppb3222ND - 5.20 ppb
20172.64 ppb3226ND - 6.90 ppb
20182.04 ppb3230ND - 4.20 ppb
20191.99 ppb3226ND - 5.30 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.15 ppb

The health guideline of 0.15 parts per billion, or ppb, for the group of four trihalomethanes, or THM4/TTHM, was defined in a peer-reviewed scientific study by EWG and represents a one-in-one-million lifetime cancer risk level.

EPA Maximum Contaminant
Level (MCL) 80 ppb

The legal limit for the group of four trihalomethanes, established in 1998, was based on the need for residual disinfectant levels in water served to customers and the cost of treatment. This limit does not fully protect against the risk of cancer due to exposure to trihalomethanes.

ppb = parts per billion

All test results

Date Lab ID Result
2014-01-062011557382.15 ppb
2014-01-062011557390.500 ppb
2014-01-062011557401.60 ppb
2014-01-062011557413.70 ppb
2014-01-062011557382.15 ppb
2014-01-062011557390.500 ppb
2014-01-062011557401.60 ppb
2014-01-062011557413.70 ppb
2014-04-102025520014.10 ppb
2014-04-10202552002ND
2014-04-102025520035.40 ppb
2014-04-102025520043.60 ppb
2014-04-102025520014.10 ppb
2014-04-10202552002ND
2014-04-102025520035.40 ppb
2014-04-102025520043.60 ppb
2014-07-102065910011.60 ppb
2014-07-10206591002ND
2014-07-102065910031.50 ppb
2014-07-102065910048.00 ppb
2014-07-102065910011.60 ppb
2014-07-10206591002ND
2014-07-102065910031.50 ppb
2014-07-102065910048.00 ppb
2014-10-0620105410015.60 ppb
2014-10-0620105410024.00 ppb
2014-10-062010541003ND
2014-10-0620105410041.90 ppb
2014-10-0620105410015.60 ppb
2014-10-0620105410024.00 ppb
2014-10-062010541003ND
2014-10-0620105410041.90 ppb
2015-01-0920145120012.40 ppb
2015-01-0920145120022.00 ppb
2015-01-0920146120033.20 ppb
2015-01-0920146120041.000 ppb
2015-01-0920145120012.40 ppb
2015-01-0920145120022.00 ppb
2015-01-0920146120033.20 ppb
2015-01-0920146120041.000 ppb
2015-04-0920183720011.90 ppb
2015-04-0920183720021.10 ppb
2015-04-0920183720035.10 ppb
2015-04-0920183720045.20 ppb
2015-04-0920183720011.90 ppb
2015-04-0920183720021.10 ppb
2015-04-0920183720035.10 ppb
2015-04-0920183720045.20 ppb
2015-07-0720223760016.50 ppb
2015-07-072022376002ND
2015-07-0720223760035.90 ppb
2015-07-07202237600414.1 ppb
2015-07-0720223760016.50 ppb
2015-07-072022376002ND
2015-07-0720223760035.90 ppb
2015-07-07202237600414.1 ppb
2015-10-0620267880011.50 ppb
2015-10-062026788002ND
2015-10-0620267880031.40 ppb
2015-10-0620267880042.90 ppb
2015-10-0620267880011.50 ppb
2015-10-062026788002ND
2015-10-0620267880031.40 ppb
2015-10-0620267880042.90 ppb
2016-01-0420307200011.10 ppb
2016-01-042030720002ND
2016-01-0420307200031.40 ppb
2016-01-0420307200042.60 ppb
2016-01-0420307200011.10 ppb
2016-01-042030720002ND
2016-01-0420307200031.40 ppb
2016-01-0420307200042.60 ppb
2016-04-072034973001ND
2016-04-0720349740013.10 ppb
2016-04-072034975001ND
2016-04-072034976001ND
2016-04-072034973001ND
2016-04-0720349740013.10 ppb
2016-04-072034975001ND
2016-04-072034976001ND
2016-07-0620394230010.650 ppb
2016-07-0620394290011.60 ppb
2016-07-0620394300015.20 ppb
2016-07-062039480014.00 ppb
2016-07-0620394230010.650 ppb
2016-07-0620394290011.60 ppb
2016-07-0620394300015.20 ppb
2016-07-062039480014.00 ppb
2016-10-1020439520012.10 ppb
2016-10-102043953001ND
2016-10-1020439550011.30 ppb
2016-10-1020439560013.70 ppb
2016-10-1020439520012.10 ppb
2016-10-102043953001ND
2016-10-1020439550011.30 ppb
2016-10-1020439560013.70 ppb
2017-01-13352888720010.840 ppb
2017-01-1335288872002ND
2017-01-13352888720031.000 ppb
2017-01-1335288872004ND
2017-01-13352888720010.840 ppb
2017-01-1335288872002ND
2017-01-13352888720031.000 ppb
2017-01-1335288872004ND
2017-04-05353051640012.40 ppb
2017-04-05353051640023.90 ppb
2017-04-05353051640033.20 ppb
2017-04-05353051640046.90 ppb
2017-04-05353051640012.40 ppb
2017-04-05353051640023.90 ppb
2017-04-05353051640033.20 ppb
2017-04-05353051640046.90 ppb
2017-07-06353225150295.60 ppb
2017-07-06353225150301.80 ppb
2017-07-0635322515031ND
2017-07-06353225150322.20 ppb
2017-07-06353225150295.60 ppb
2017-07-06353225150301.80 ppb
2017-07-0635322515031ND
2017-07-06353225150322.20 ppb
2017-10-04353405060014.20 ppb
2017-10-04353405060020.610 ppb
2017-10-04353405060034.50 ppb
2017-10-04353405060045.10 ppb
2017-10-04353405060014.20 ppb
2017-10-04353405060020.610 ppb
2017-10-04353405060034.50 ppb
2017-10-04353405060045.10 ppb
2018-01-12353684070012.80 ppb
2018-01-12353684070021.70 ppb
2018-01-12353684070030.800 ppb
2018-01-12353684070041.40 ppb
2018-01-12353684070012.80 ppb
2018-01-12353684070021.70 ppb
2018-01-12353684070030.800 ppb
2018-01-12353684070041.40 ppb
2018-04-05353846300012.20 ppb
2018-04-05353846300020.520 ppb
2018-04-05353846300032.90 ppb
2018-04-05353846300044.20 ppb
2018-04-05353846300012.20 ppb
2018-04-05353846300020.520 ppb
2018-04-05353846300032.90 ppb
2018-04-05353846300044.20 ppb
2018-07-05354025390012.60 ppb
2018-07-05354025390023.30 ppb
2018-07-05354025390033.50 ppb
2018-07-05354025390042.60 ppb
2018-07-05354025390012.60 ppb
2018-07-05354025390023.30 ppb
2018-07-05354025390033.50 ppb
2018-07-05354025390042.60 ppb
2018-10-04354225490011.70 ppb
2018-10-0435422549002ND
2018-10-04354225490031.10 ppb
2018-10-04354225490041.30 ppb
2018-10-04354225490011.70 ppb
2018-10-0435422549002ND
2018-10-04354225490031.10 ppb
2018-10-04354225490041.30 ppb
2019-01-11354418650012.50 ppb
2019-01-11354418650020.510 ppb
2019-01-11354418650032.60 ppb
2019-01-11354418650042.50 ppb
2019-01-11354418650012.50 ppb
2019-01-11354418650020.510 ppb
2019-01-11354418650032.60 ppb
2019-01-11354418650042.50 ppb
2019-04-05354599590011.60 ppb
2019-04-0535459959002ND
2019-04-05354599590031.30 ppb
2019-04-05354599590041.20 ppb
2019-04-05354599590011.60 ppb
2019-04-0535459959002ND
2019-04-05354599590031.30 ppb
2019-04-05354599590041.20 ppb
2019-07-19354836710013.00 ppb
2019-07-1935483671002ND
2019-07-19354836710032.70 ppb
2019-07-19354836710043.00 ppb
2019-07-19354836710013.00 ppb
2019-07-1935483671002ND
2019-07-19354836710032.70 ppb
2019-07-19354836710043.00 ppb
2019-10-04355028580015.30 ppb
2019-10-0435502858002ND
2019-10-04355028580033.00 ppb
2019-10-04355028580042.60 ppb
2019-10-04355028580015.30 ppb
2019-10-0435502858002ND
2019-10-04355028580033.00 ppb
2019-10-04355028580042.60 ppb