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EWG's Tap Water Database — 2019 UPDATE

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Total trihalomethanes (TTHMs)

Florin County Water District

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.

 

31

Samples

0

Samples exceeding legal limit (MCL)

4

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20121.20 ppb221.000 ppb - 1.40 ppb
20131.70 ppb41ND - 6.80 ppb
2014ND70ND
20150.333 ppb181ND - 6.00 ppb
2016N/A00N/A
2017N/A00N/A

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
2012-05-305810-009-09561.000 ppb
2012-08-295810-003-09371.40 ppb
2013-04-155810-012-13256.80 ppb
2013-07-185810-007-0914ND
2013-12-125810-007-0950ND
2013-12-125810-006-1427ND
2014-04-305810-002-1017ND
2014-04-305810-003-0927ND
2014-04-305810-004-1054ND
2014-04-305810-006-1241ND
2014-04-305810-007-0841ND
2014-04-305810-009-1200ND
2014-08-075810-010-1305ND
2015-02-115810-012-0948ND
2015-02-115810-010-1305ND
2015-02-115810-006-1402ND
2015-02-110013-007-09066.00 ppb
2015-02-115810-007-0906ND
2015-02-115810-004-1115ND
2015-02-115810-009-1216ND
2015-05-275810-009-1159ND
2015-05-275810-012-0923ND
2015-05-275810-004-1053ND
2015-05-275810-006-1258ND
2015-05-275810-003-1012ND
2015-09-235810-003-1044ND
2015-09-235810-004-1147ND
2015-09-235810-006-1336ND
2015-09-235810-007-0932ND
2015-09-235810-012-1009ND
2015-09-235810-009-1247ND