Menu

EWG's Tap Water Database — 2019 UPDATE

Donate

Total trihalomethanes (TTHMs)

California Water Service (CWS) - Salinas

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.

 

139

Samples

0

Samples exceeding legal limit (MCL)

111

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20121.49 ppb1816ND - 4.40 ppb
20131.93 ppb2422ND - 5.90 ppb
20141.32 ppb2523ND - 3.80 ppb
20151.47 ppb2418ND - 5.90 ppb
20161.18 ppb2416ND - 4.50 ppb
20171.58 ppb2416ND - 4.80 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
2012-04-185701-804-16152.40 ppb
2012-04-185701-805-10061.000 ppb
2012-04-185701-806-1054ND
2012-04-195701-801-15310.700 ppb
2012-04-195701-802-11481.10 ppb
2012-04-195701-803-11254.30 ppb
2012-07-175701-801-16050.600 ppb
2012-07-175701-802-15100.700 ppb
2012-07-175701-803-11054.40 ppb
2012-07-185701-804-10152.70 ppb
2012-07-185701-805-14351.20 ppb
2012-07-185701-806-13400.600 ppb
2012-10-165701-801-15400.500 ppb
2012-10-165701-802-10281.20 ppb
2012-10-165701-803-10460.700 ppb
2012-10-175701-804-11042.50 ppb
2012-10-175701-805-14422.30 ppb
2012-10-175701-806-1547ND
2013-01-235701-804-10102.60 ppb
2013-01-235701-805-10592.30 ppb
2013-01-235701-806-1310ND
2013-01-245701-801-11255.90 ppb
2013-01-245701-802-16051.70 ppb
2013-01-245701-803-13051.80 ppb
2013-04-185701-801-15210.900 ppb
2013-04-185701-802-10401.40 ppb
2013-04-185701-803-11171.20 ppb
2013-04-185701-804-15443.60 ppb
2013-04-185701-805-14351.80 ppb
2013-04-185701-806-11015.20 ppb
2013-07-145701-801-13352.20 ppb
2013-07-145701-802-12000.700 ppb
2013-07-145701-803-13100.500 ppb
2013-07-145701-804-14053.30 ppb
2013-07-145701-805-11301.90 ppb
2013-07-145701-806-12500.900 ppb
2013-10-175701-801-09351.30 ppb
2013-10-175701-802-13450.700 ppb
2013-10-175701-803-1248ND
2013-10-175701-804-11202.70 ppb
2013-10-175701-805-14502.40 ppb
2013-10-175701-806-14021.40 ppb
2014-01-235701-801-11523.80 ppb
2014-01-235701-802-13320.900 ppb
2014-01-235701-803-12510.800 ppb
2014-01-235701-804-10301.20 ppb
2014-01-235701-805-14041.30 ppb
2014-01-235701-806-13091.70 ppb
2014-04-235701-801-14301.70 ppb
2014-04-235701-802-10402.40 ppb
2014-04-235701-803-10251.20 ppb
2014-04-235701-804-13160.900 ppb
2014-04-235701-805-11301.90 ppb
2014-04-235701-806-10052.80 ppb
2014-07-225701-801-14401.000 ppb
2014-07-225701-802-11441.70 ppb
2014-07-225701-803-1100ND
2014-07-225701-804-09391.10 ppb
2014-07-225701-805-14041.20 ppb
2014-07-225701-806-13351.10 ppb
2014-07-305701-805-14000.800 ppb
2014-10-205701-801-09300.800 ppb
2014-10-205701-802-14400.700 ppb
2014-10-205701-803-14270.500 ppb
2014-10-205701-804-14070.700 ppb
2014-10-205701-805-15022.70 ppb
2014-10-205701-806-1248ND
2015-01-215701-801-09055.00 ppb
2015-01-215701-802-0905ND
2015-01-215701-803-09055.90 ppb
2015-01-215701-804-09050.700 ppb
2015-01-215701-805-09052.70 ppb
2015-01-215701-806-0905ND
2015-04-215701-801-07561.10 ppb
2015-04-215701-802-07560.600 ppb
2015-04-215701-803-07562.90 ppb
2015-04-215701-804-07560.700 ppb
2015-04-215701-805-07562.10 ppb
2015-04-215701-806-0756ND
2015-07-215701-801-08511.50 ppb
2015-07-215701-802-08511.10 ppb
2015-07-215701-804-08510.700 ppb
2015-07-215701-805-08511.000 ppb
2015-07-215701-806-08512.30 ppb
2015-07-235701-803-08150.500 ppb
2015-10-215701-801-08180.900 ppb
2015-10-215701-802-08183.80 ppb
2015-10-215701-803-0818ND
2015-10-215701-804-0818ND
2015-10-215701-805-08181.70 ppb
2015-10-215701-806-0818ND
2016-01-205701-801-08454.50 ppb
2016-01-205701-802-08450.900 ppb
2016-01-205701-803-08452.80 ppb
2016-01-205701-804-08450.600 ppb
2016-01-205701-805-08452.10 ppb
2016-01-205701-806-0845ND
2016-04-195701-801-0942ND
2016-04-195701-802-09421.60 ppb
2016-04-195701-803-0942ND
2016-04-195701-804-09420.900 ppb
2016-04-195701-805-09422.00 ppb
2016-04-195701-806-0942ND
2016-07-195701-801-08240.800 ppb
2016-07-195701-802-0824ND
2016-07-195701-803-08241.000 ppb
2016-07-195701-804-08241.10 ppb
2016-07-195701-805-08241.10 ppb
2016-07-195701-806-08241.70 ppb
2016-10-135701-801-08022.30 ppb
2016-10-135701-802-0802ND
2016-10-135701-803-0802ND
2016-10-135701-804-0802ND
2016-10-135701-805-08021.80 ppb
2016-10-135701-806-08023.20 ppb
2017-01-195701-801-08304.40 ppb
2017-01-195701-802-08302.20 ppb
2017-01-195701-803-08304.80 ppb
2017-01-195701-804-08300.700 ppb
2017-01-195701-805-08303.30 ppb
2017-01-195701-806-0830ND
2017-04-195810-801-09024.20 ppb
2017-04-195810-802-12232.70 ppb
2017-04-195810-803-12521.40 ppb
2017-04-195810-804-0915ND
2017-04-195810-805-11462.60 ppb
2017-04-195810-806-1235ND
2017-07-185810-801-11132.30 ppb
2017-07-185810-802-10071.20 ppb
2017-07-185810-803-10310.780 ppb
2017-07-185810-804-1141ND
2017-07-185810-805-13381.70 ppb
2017-07-185810-806-10172.10 ppb
2017-10-165810-801-13410.670 ppb
2017-10-165810-802-1143ND
2017-10-165810-803-1200ND
2017-10-165810-804-1706ND
2017-10-165810-805-17472.80 ppb
2017-10-165810-806-1105ND