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EWG's Tap Water Database — 2019 UPDATE

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Chloroform

City of Hollister

Chloroform, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Chloroform and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Read More.

In addition to tap water disinfection, chloroform pollution in the environment also comes from industrial discharges from pulp and paper mills, and from urban wastewater effluent. Human studies show that chloroform damages the kidneys, liver and central nervous system. In animals, chloroform causes infertility, birth defects and cancer.

Click here to read more about disinfection byproducts.

 

73

Samples

0

Samples exceeding legal limit (MCL)

11

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2012N/A00N/A
20131.21 ppb440.950 ppb - 1.70 ppb
20140.477 ppb162ND - 6.98 ppb
2015ND160ND
2016ND210ND
20170.598 ppb165ND - 2.80 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.4 ppb

The EWG Health Guideline of 0.4 ppb for chloroform was proposed in 2018 by the California Office of Environmental Health Hazard Assessment as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.

ppb = parts per billion

All test results

Date Lab ID Result
2013-12-111610-801-15351.70 ppb
2013-12-111610-803-14550.950 ppb
2013-12-111610-802-15100.960 ppb
2013-12-111610-804-16101.24 ppb
2014-03-241610-804-16500.650 ppb
2014-03-241610-802-1615ND
2014-03-241610-803-1555ND
2014-03-241610-801-17106.98 ppb
2014-06-061610-802-1520ND
2014-06-061610-803-1540ND
2014-06-061610-804-1458ND
2014-06-061610-801-1445ND
2014-10-091610-801-1150ND
2014-10-091610-802-1100ND
2014-10-091610-803-1130ND
2014-10-091610-804-1205ND
2014-12-181610-802-1255ND
2014-12-181610-803-1310ND
2014-12-181610-804-1220ND
2014-12-181610-801-1235ND
2015-04-211610-803-1328ND
2015-04-211610-804-1341ND
2015-04-211610-801-1350ND
2015-04-211610-802-1321ND
2015-07-091610-804-0954ND
2015-07-091610-802-0843ND
2015-07-091610-803-0903ND
2015-07-091610-801-1008ND
2015-09-161610-804-1422ND
2015-09-161610-801-1440ND
2015-09-161610-803-1359ND
2015-09-161610-802-1344ND
2015-11-121610-804-0858ND
2015-11-121610-803-0932ND
2015-11-121610-801-0840ND
2015-11-121610-802-0920ND
2016-03-031610-801-0913ND
2016-03-031610-802-0817ND
2016-03-031610-804-0856ND
2016-03-031610-803-0829ND
2016-06-141610-801-1442ND
2016-06-141610-802-1428ND
2016-06-141610-803-1421ND
2016-06-141610-804-1523ND
2016-06-291610-804-1123ND
2016-07-071610-804-1237ND
2016-07-141610-804-1245ND
2016-07-211610-804-1015ND
2016-08-041610-804-1320ND
2016-09-221610-804-1205ND
2016-09-221610-801-1155ND
2016-09-221610-802-1110ND
2016-09-221610-803-1100ND
2016-12-141610-803-1237ND
2016-12-141610-802-1251ND
2016-12-141610-801-1309ND
2016-12-141610-804-1316ND
2017-03-011610-803-1209ND
2017-03-011610-801-1150ND
2017-03-011610-802-1202ND
2017-03-011610-804-11411.08 ppb
2017-06-011610-801-1245ND
2017-06-011610-802-1159ND
2017-06-011610-803-1210ND
2017-06-011610-804-1226ND
2017-09-071610-804-1142ND
2017-09-071610-801-1148ND
2017-09-071610-802-1202ND
2017-09-071610-803-1208ND
2017-12-071610-801-09142.80 ppb
2017-12-071610-804-09052.29 ppb
2017-12-071610-802-09341.65 ppb
2017-12-071610-803-09261.75 ppb