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EWG's Tap Water Database — 2019 UPDATE

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Total trihalomethanes (TTHMs)

Sandy City 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.

 

140

Samples

0

Samples exceeding legal limit (MCL)

106

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
201212.9 ppb1810ND - 51.9 ppb
201320.7 ppb3332ND - 41.5 ppb
20146.81 ppb2616ND - 19.4 ppb
201523.7 ppb2218ND - 61.6 ppb
201615.4 ppb2315ND - 39.1 ppb
201729.0 ppb1816ND - 70.7 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 Result
2012-06-15ND
2012-08-02ND
2012-08-03ND
2012-08-07ND
2012-08-08ND
2012-08-09ND
2012-08-280.700 ppb
2012-09-0511.1 ppb
2012-10-0130.0 ppb
2012-10-0142.1 ppb
2012-10-0119.2 ppb
2012-10-0151.9 ppb
2012-10-017.00 ppb
2012-10-01ND
2012-10-0135.4 ppb
2012-10-0132.6 ppb
2012-10-251.50 ppb
2012-11-27ND
2013-01-0321.1 ppb
2013-01-0315.2 ppb
2013-01-0318.3 ppb
2013-01-0318.6 ppb
2013-01-0317.3 ppb
2013-01-0310.3 ppb
2013-01-0314.6 ppb
2013-01-037.60 ppb
2013-04-0121.6 ppb
2013-04-0118.2 ppb
2013-04-0112.3 ppb
2013-04-0116.1 ppb
2013-04-0113.7 ppb
2013-04-0111.1 ppb
2013-04-0129.4 ppb
2013-04-018.60 ppb
2013-06-18ND
2013-07-0225.6 ppb
2013-07-0210.7 ppb
2013-07-0235.6 ppb
2013-07-0238.9 ppb
2013-07-0230.7 ppb
2013-07-0231.2 ppb
2013-07-0210.7 ppb
2013-07-0233.2 ppb
2013-10-0122.4 ppb
2013-10-0124.5 ppb
2013-10-0126.8 ppb
2013-10-0118.9 ppb
2013-10-0124.3 ppb
2013-10-0116.3 ppb
2013-10-0137.0 ppb
2013-10-0141.5 ppb
2014-01-0219.4 ppb
2014-01-0216.1 ppb
2014-01-0214.9 ppb
2014-01-0212.3 ppb
2014-01-029.10 ppb
2014-01-028.00 ppb
2014-01-0217.8 ppb
2014-01-027.40 ppb
2014-02-20ND
2014-04-031.70 ppb
2014-04-0314.6 ppb
2014-04-03ND
2014-04-03ND
2014-04-0312.0 ppb
2014-04-03ND
2014-04-0317.3 ppb
2014-04-03ND
2014-05-290.150 ppb
2014-05-30ND
2014-06-05ND
2014-06-06ND
2014-07-21ND
2014-07-23ND
2014-07-238.40 ppb
2014-07-237.30 ppb
2014-07-2310.6 ppb
2015-01-0922.3 ppb
2015-01-0919.2 ppb
2015-01-0928.4 ppb
2015-01-0930.0 ppb
2015-04-06ND
2015-04-0723.7 ppb
2015-04-0730.3 ppb
2015-04-0725.4 ppb
2015-04-0722.6 ppb
2015-07-060.350 ppb
2015-07-0735.5 ppb
2015-07-0729.5 ppb
2015-07-0730.8 ppb
2015-07-0724.8 ppb
2015-07-14ND
2015-07-16ND
2015-07-225.20 ppb
2015-10-0561.6 ppb
2015-10-0552.8 ppb
2015-10-0542.3 ppb
2015-10-0536.7 ppb
2015-11-09ND
2016-01-2228.1 ppb
2016-01-2211.0 ppb
2016-01-2221.6 ppb
2016-01-2217.9 ppb
2016-03-11ND
2016-04-196.70 ppb
2016-04-1916.4 ppb
2016-04-196.20 ppb
2016-04-19ND
2016-04-22ND
2016-06-06ND
2016-06-14ND
2016-06-17ND
2016-06-21ND
2016-06-22ND
2016-07-1928.0 ppb
2016-07-1935.2 ppb
2016-07-1927.6 ppb
2016-07-1933.3 ppb
2016-10-0635.7 ppb
2016-10-0635.4 ppb
2016-10-0612.1 ppb
2016-10-0639.1 ppb
2017-01-2023.2 ppb
2017-01-2024.9 ppb
2017-01-2020.3 ppb
2017-01-2013.8 ppb
2017-04-2827.4 ppb
2017-04-2822.8 ppb
2017-04-2823.7 ppb
2017-04-2821.7 ppb
2017-06-22ND
2017-08-1743.7 ppb
2017-08-1748.4 ppb
2017-08-1733.4 ppb
2017-08-1770.7 ppb
2017-09-01ND
2017-10-3041.5 ppb
2017-10-3050.0 ppb
2017-10-3026.9 ppb
2017-10-3029.1 ppb