Menu

EWG's Tap Water Database — 2019 UPDATE

Donate

Total trihalomethanes (TTHMs)

City of Pocatello

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.

 

120

Samples

0

Samples exceeding legal limit (MCL)

101

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20128.85 ppb16161.82 ppb - 23.9 ppb
201311.6 ppb16161.39 ppb - 18.7 ppb
201412.5 ppb16165.53 ppb - 21.7 ppb
201511.5 ppb16164.74 ppb - 17.1 ppb
20165.85 ppb3220ND - 18.8 ppb
20178.13 ppb2417ND - 20.9 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
2012-02-23DI2021050111.7 ppb
2012-02-23DI202108017.52 ppb
2012-02-23DI2021060111.1 ppb
2012-02-23DI2021070110.9 ppb
2012-06-04DI206045011.82 ppb
2012-06-04DI206044016.11 ppb
2012-06-04DI206043016.46 ppb
2012-06-04DI206042018.12 ppb
2012-08-07DI208038018.11 ppb
2012-08-07DI208038022.31 ppb
2012-08-07DI208038036.07 ppb
2012-08-07DI208038047.52 ppb
2012-11-14DI211062018.14 ppb
2012-11-14DI211062024.93 ppb
2012-11-14DI2110620323.9 ppb
2012-11-14DI2110620416.9 ppb
2013-02-06DI302022019.40 ppb
2013-02-06DI3020220214.0 ppb
2013-02-06DI3020220313.7 ppb
2013-02-06DI3020220415.5 ppb
2013-05-08DI3050410112.0 ppb
2013-05-08DI3050400111.2 ppb
2013-05-08DI3050390111.4 ppb
2013-05-08DI305038018.64 ppb
2013-08-14DI308088017.55 ppb
2013-08-14DI308088021.39 ppb
2013-08-14DI308088046.47 ppb
2013-08-14DI308088057.14 ppb
2013-11-18DI3110570118.0 ppb
2013-11-18DI3110580118.7 ppb
2013-11-18DI3110600117.7 ppb
2013-11-18DI3110590113.2 ppb
2014-03-19DI4031070118.7 ppb
2014-03-19DI4031040115.8 ppb
2014-03-19DI403105017.42 ppb
2014-03-19DI4031060115.4 ppb
2014-06-04DI406030016.99 ppb
2014-06-04DI406029015.53 ppb
2014-06-04DI406027017.54 ppb
2014-06-04DI406028018.10 ppb
2014-08-12DI408075019.11 ppb
2014-08-12DI408075029.78 ppb
2014-08-12DI408075038.77 ppb
2014-08-12DI4080750413.1 ppb
2014-11-03DI4110020121.7 ppb
2014-11-03DI4110020217.8 ppb
2014-11-03DI4110020319.6 ppb
2014-11-03DI4110020414.0 ppb
2015-02-25DI5021230110.8 ppb
2015-02-25DI5021230213.1 ppb
2015-02-25DI5021230312.5 ppb
2015-02-25DI5021230410.7 ppb
2015-06-04DI5060400117.1 ppb
2015-06-04DI5060400210.00 ppb
2015-06-04DI5060400314.2 ppb
2015-06-04DI506040045.54 ppb
2015-08-05DI5080230112.1 ppb
2015-08-05DI508023027.89 ppb
2015-08-05DI508023038.91 ppb
2015-08-05DI508023044.74 ppb
2015-11-03DI5110120115.2 ppb
2015-11-03DI5110120210.7 ppb
2015-11-03DI5110120315.9 ppb
2015-11-03DI5110120414.3 ppb
2016-03-09DI6030520113.8 ppb
2016-03-09DI6030520211.9 ppb
2016-03-09DI603052038.48 ppb
2016-03-09DI6030520413.7 ppb
2016-05-10DI6050590110.4 ppb
2016-05-10DI6050590212.2 ppb
2016-05-10DI6050590311.7 ppb
2016-05-10DI605059048.92 ppb
2016-08-30DI608341011.66 ppb
2016-08-30DI608341025.69 ppb
2016-08-30DI608341038.90 ppb
2016-08-30DI608341048.34 ppb
2016-10-17VI61012201ND
2016-10-17VI61012202ND
2016-10-17VI61012203ND
2016-10-17VI61012204ND
2016-10-17VI61012205ND
2016-10-17VI610122060.810 ppb
2016-10-17VI610122072.94 ppb
2016-10-17VI61012208ND
2016-10-17VI61012209ND
2016-10-17VI610122105.75 ppb
2016-10-17VI61012211ND
2016-10-17VI61012212ND
2016-10-17VI61012213ND
2016-10-17VI61012215ND
2016-10-17VI61012216ND
2016-10-18VI610132012.00 ppb
2016-11-14DI6110950118.8 ppb
2016-11-14DI6110950210.9 ppb
2016-11-14DI6110960113.3 ppb
2016-11-14DI6110960217.0 ppb
2017-03-07DI7030500112.0 ppb
2017-03-07DI7030500211.9 ppb
2017-03-07DI7030500314.2 ppb
2017-03-07DI703050048.06 ppb
2017-06-14DI706170016.59 ppb
2017-06-14DI7061700213.3 ppb
2017-06-14DI7061700311.4 ppb
2017-06-14DI7061700411.4 ppb
2017-08-30DI708288015.45 ppb
2017-08-30DI7082880212.1 ppb
2017-08-30DI7082880310.8 ppb
2017-08-30DI708288049.33 ppb
2017-10-04VI710049021.02 ppb
2017-10-04VI71004903ND
2017-10-04VI71004904ND
2017-10-04VI71004905ND
2017-10-04VI71004906ND
2017-10-05VI71004901ND
2017-10-05VI71004907ND
2017-10-05VI71004908ND
2017-10-05DI7100530120.9 ppb
2017-10-05DI7100530217.9 ppb
2017-10-05DI7100530318.9 ppb
2017-10-05DI710053049.95 ppb