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EWG's Tap Water Database — 2021 UPDATE

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Total trihalomethanes (TTHMs)

Avon Water Company

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

 

97

Samples

0

Samples exceeding legal limit (MCL)

95

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2013N/A00N/A
20146.03 ppb16163.40 ppb - 14.0 ppb
20155.03 ppb16160.720 ppb - 13.0 ppb
20167.20 ppb16161.43 ppb - 12.8 ppb
20178.10 ppb16163.80 ppb - 18.2 ppb
20186.43 ppb1716ND - 12.0 ppb
20197.84 ppb1615ND - 18.0 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
2014-01-16E401A25-2TTHM4.60 ppb
2014-01-16E401A25-3TTHM4.50 ppb
2014-01-16E401A25-4TTHM7.40 ppb
2014-01-16E401A25-1TTHM4.40 ppb
2014-04-15E404E43-1TTHM4.90 ppb
2014-04-15E404E43-2TTHM5.50 ppb
2014-04-15E404E43-3TTHM4.20 ppb
2014-04-15E404E43-4TTHM3.40 ppb
2014-07-14E407C09-1GE5.30 ppb
2014-07-14E407C09-2GE6.10 ppb
2014-07-14E407C09-3GE14.0 ppb
2014-07-14E407C09-4GE3.40 ppb
2014-10-16E410F41-2TTHM6.50 ppb
2014-10-16E410F41-4TTHM6.30 ppb
2014-10-16E410F41-3TTHM9.20 ppb
2014-10-16E410F41-1TTHM6.70 ppb
2015-01-15E501A25-2TTHM3.60 ppb
2015-01-15E501A25-1TTHM2.70 ppb
2015-01-15E501A25-3TTHM3.40 ppb
2015-01-15E501A25-4TTHM3.30 ppb
2015-04-14E504E21-2TTHM3.50 ppb
2015-04-14E504E21-4TTHM1.38 ppb
2015-04-14E504E21-3TTHM3.00 ppb
2015-04-14E504E21-1TTHM4.20 ppb
2015-07-15E507G94-1TTHM4.10 ppb
2015-07-15E507G94-3TTHM13.0 ppb
2015-07-15E507G94-4TTHM2.10 ppb
2015-07-15E507G94-2TTHM7.00 ppb
2015-10-15E510E91-4TTHM0.720 ppb
2015-10-15E510E91-3TTHM8.40 ppb
2015-10-15E510E91-1TTHM8.80 ppb
2015-10-15E510E91-2TTHM11.2 ppb
2016-01-15E601D17-1TTHM6.70 ppb
2016-01-15E601D17-2TTHM5.60 ppb
2016-01-15E601D17-3TTHM7.20 ppb
2016-01-15E601D17-4TTHM1.70 ppb
2016-04-19E605079-3TTHM9.40 ppb
2016-04-19E605079-4TTHM5.60 ppb
2016-04-19E605079-2TTHM6.60 ppb
2016-04-19E605079-1TTHM6.90 ppb
2016-07-13E607C00-1TTHM8.90 ppb
2016-07-13E607C00-2TTHM6.70 ppb
2016-07-13E607C00-3TTHM12.0 ppb
2016-07-13E607C00-4TTHM1.43 ppb
2016-10-14E610G73-1TTHM8.50 ppb
2016-10-14E610G73-2TTHM10.00 ppb
2016-10-14E610G73-3TTHM12.8 ppb
2016-10-14E610G73-4TTHM5.20 ppb
2017-01-13E701C67-4TTHM5.00 ppb
2017-01-13E701C67-1TTHM9.20 ppb
2017-01-13E701C67-2TTHM5.80 ppb
2017-01-13E701C67-3TTHM4.80 ppb
2017-04-13D7D1107-02VOC9.50 ppb
2017-04-13D7D1107-03VOC6.60 ppb
2017-04-13D7D1107-04VOC6.00 ppb
2017-04-13D7D1107-01VOC6.60 ppb
2017-07-14D7G1331-01VOC9.30 ppb
2017-07-14D7G1331-02VOC18.2 ppb
2017-07-14D7G1331-03VOC11.5 ppb
2017-07-14D7G1331-04VOC3.80 ppb
2017-10-13D7J1362-04VOC4.40 ppb
2017-10-13D7J1362-03VOC8.60 ppb
2017-10-13D7J1362-02VOC8.50 ppb
2017-10-13D7J1362-01VOC11.8 ppb
2018-01-24D8A1669-01VOC6.00 ppb
2018-01-24D8A1669-02VOC5.50 ppb
2018-01-24D8A1669-03VOC7.20 ppb
2018-01-24D8A1669-04VOC3.50 ppb
2018-04-25D8D2151-08VOC0.800 ppb
2018-04-25D8D2151-09VOC12.0 ppb
2018-04-25D8D2151-10VOC7.10 ppb
2018-04-25D8D2151-11VOC9.90 ppb
2018-07-26CA9874610.7 ppb
2018-07-26CA9874410.6 ppb
2018-07-26CA987430.630 ppb
2018-07-26CA987455.03 ppb
2018-10-09DBP 2005086646.60 ppb
2018-10-09DBP 2005086656.10 ppb
2018-10-09DBP 2005086767.80 ppb
2018-10-09DBP 2005086789.90 ppb
2018-10-09VOC1 200508699ND
2019-01-08DBP 2005181314.90 ppb
2019-01-08DBP 200518132ND
2019-01-08DBP 2005181334.40 ppb
2019-01-08DBP 2005181353.60 ppb
2019-04-11DBP 2005282675.80 ppb
2019-04-11DBP 2005282708.00 ppb
2019-04-11DBP 2005282697.70 ppb
2019-04-11DBP 20052826812.2 ppb
2019-07-02DBP 2005389922.70 ppb
2019-07-02DBP 20053899315.0 ppb
2019-07-02DBP 2005389958.50 ppb
2019-07-02DBP 20053899611.9 ppb
2019-10-03DBP 2005514292.60 ppb
2019-10-03DBP 20055143018.0 ppb
2019-10-03DBP 2005514318.40 ppb
2019-10-03DBP 20055143211.7 ppb