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EWG's Tap Water Database — 2021 UPDATE

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Haloacetic acids (HAA5)

California Water Service (CWS) - Los Altos Suburban

Haloacetic acids are formed when disinfectants such as chlorine are added to tap water. The group of five haloacetic acids regulated by federal standards includes monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid. Read More.

Haloacetic acids are harmful during pregnancy and may increase the risk of cancer. Haloacetic acids are� genotoxic, which means that they induce mutations and DNA damage. Multiple studies by the National Toxicology Program have demonstrated the cancer-causing properties of individual haloacetic acids in laboratory animals. The Department of Health and Human Services is currently considering listing di- or tri-haloacetic acids for possible inclusion in its comprehensive Report on Carcinogens.

Click here to read more about disinfection byproducts.

MORE ABOUT THIS CONTAMINANT

 

193

Samples

1

Samples exceeding legal limit (MCL)

146

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2013N/A00N/A
20146.86 ppb3323ND - 29.5 ppb
20157.85 ppb3225ND - 24.0 ppb
201612.8 ppb3229ND - 32.0 ppb
201710.2 ppb3225ND - 33.0 ppb
20189.49 ppb3224ND - 64.0 ppb
20197.56 ppb3220ND - 17.0 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.1 ppb

The EWG Health Guideline of 0.1 ppb for the group of five haloacetic acids, or HAA5, was defined in a peer-reviewed scientific study by EWG and represents a one-in-a-million lifetime cancer risk level. This health guideline protects against cancer.

EPA Maximum Contaminant
Level (MCL) 60 ppb

The legal limit for the group of five haloacetic acids (HAA5), 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 and harm to the developing fetus due to exposure to haloacetic acids.

ppb = parts per billion

All test results

Date Lab ID Result
2014-02-135810-900-12075.60 ppb
2014-02-135810-901-1324ND
2014-02-135810-902-11106.30 ppb
2014-02-135810-903-13463.20 ppb
2014-02-135810-904-13082.60 ppb
2014-02-135810-905-12437.60 ppb
2014-02-135810-906-1134ND
2014-02-135810-907-1152ND
2014-04-081610-903-085029.5 ppb
2014-05-155810-900-13367.70 ppb
2014-05-155810-901-1435ND
2014-05-155810-902-123114.0 ppb
2014-05-155810-903-145921.0 ppb
2014-05-155810-904-14084.90 ppb
2014-05-155810-905-135012.0 ppb
2014-05-155810-906-12486.90 ppb
2014-05-155810-907-13107.90 ppb
2014-08-075810-900-12289.40 ppb
2014-08-075810-901-1335ND
2014-08-075810-902-114113.0 ppb
2014-08-075810-903-140314.0 ppb
2014-08-075810-904-142910.00 ppb
2014-08-075810-905-124613.0 ppb
2014-08-075810-906-1111ND
2014-08-075810-907-120413.0 ppb
2014-11-125810-900-1315ND
2014-11-125810-901-1435ND
2014-11-125810-902-10424.70 ppb
2014-11-125810-903-135713.0 ppb
2014-11-125810-904-1332ND
2014-11-125810-905-12524.90 ppb
2014-11-125810-906-1144ND
2014-11-125810-907-12202.10 ppb
2015-02-095810-900-1619ND
2015-02-095810-901-1333ND
2015-02-095810-902-1705ND
2015-02-095810-903-130410.00 ppb
2015-02-095810-904-12202.20 ppb
2015-02-095810-905-1455ND
2015-02-095810-906-17152.80 ppb
2015-02-095810-907-15502.20 ppb
2015-05-145810-900-12469.90 ppb
2015-05-145810-901-141224.0 ppb
2015-05-145810-902-105821.0 ppb
2015-05-145810-903-1435ND
2015-05-145810-904-15056.90 ppb
2015-05-145810-905-122522.0 ppb
2015-05-145810-906-11245.10 ppb
2015-05-145810-907-114716.0 ppb
2015-08-115810-900-15187.10 ppb
2015-08-115810-901-120017.0 ppb
2015-08-115810-902-135515.0 ppb
2015-08-115810-903-132318.0 ppb
2015-08-115810-904-11087.60 ppb
2015-08-115810-905-160015.0 ppb
2015-08-115810-906-14235.80 ppb
2015-08-115810-907-153312.0 ppb
2015-11-095810-900-12322.10 ppb
2015-11-095810-901-1053ND
2015-11-095810-902-1132ND
2015-11-095810-903-103515.0 ppb
2015-11-095810-904-11142.90 ppb
2015-11-095810-905-14355.30 ppb
2015-11-095810-906-13212.30 ppb
2015-11-095810-907-12563.90 ppb
2016-02-095810-900-10415.60 ppb
2016-02-095810-901-1359ND
2016-02-095810-902-14339.00 ppb
2016-02-095810-903-111430.0 ppb
2016-02-095810-904-123221.0 ppb
2016-02-095810-905-10058.10 ppb
2016-02-095810-906-15237.50 ppb
2016-02-095810-907-14587.50 ppb
2016-05-105810-901-130528.0 ppb
2016-05-105810-902-114530.0 ppb
2016-05-105810-906-120516.0 ppb
2016-05-105810-907-123022.0 ppb
2016-05-115810-900-121310.00 ppb
2016-05-115810-903-114532.0 ppb
2016-05-115810-904-112215.0 ppb
2016-05-115810-905-124424.0 ppb
2016-08-095810-900-141114.0 ppb
2016-08-095810-901-131216.0 ppb
2016-08-095810-902-102314.0 ppb
2016-08-095810-903-133016.0 ppb
2016-08-095810-904-134712.0 ppb
2016-08-095810-905-094012.0 ppb
2016-08-095810-906-143015.0 ppb
2016-08-095810-907-100714.0 ppb
2016-11-155810-900-14185.30 ppb
2016-11-155810-901-1135ND
2016-11-155810-902-12556.50 ppb
2016-11-155810-903-11505.20 ppb
2016-11-155810-904-12332.20 ppb
2016-11-155810-905-14456.30 ppb
2016-11-155810-906-1325ND
2016-11-155810-907-13485.60 ppb
2017-02-145810-900-13202.30 ppb
2017-02-145810-901-1205ND
2017-02-145810-902-15054.40 ppb
2017-02-145810-903-124020.0 ppb
2017-02-145810-904-13014.20 ppb
2017-02-145810-905-1345ND
2017-02-145810-906-1535ND
2017-02-145810-907-14217.80 ppb
2017-05-095810-901-1120ND
2017-05-095810-902-124015.0 ppb
2017-05-095810-903-114033.0 ppb
2017-05-095810-904-120922.0 ppb
2017-05-095810-905-141526.0 ppb
2017-05-095810-906-13008.50 ppb
2017-05-095810-907-133030.0 ppb
2017-05-115810-900-152922.0 ppb
2017-08-175810-900-130713.0 ppb
2017-08-175810-901-1138ND
2017-08-175810-902-133914.0 ppb
2017-08-175810-903-111415.0 ppb
2017-08-175810-904-11599.60 ppb
2017-08-175810-905-122312.0 ppb
2017-08-175810-906-14035.20 ppb
2017-08-175810-907-125015.0 ppb
2017-11-145810-900-13305.60 ppb
2017-11-145810-901-1213ND
2017-11-145810-902-135712.0 ppb
2017-11-145810-903-115217.0 ppb
2017-11-145810-904-1230ND
2017-11-145810-905-10044.40 ppb
2017-11-145810-906-14142.20 ppb
2017-11-145810-907-13094.70 ppb
2018-02-135810-901-1131ND
2018-02-135810-902-1321ND
2018-02-135810-906-12594.50 ppb
2018-02-135810-907-14259.60 ppb
2018-02-145810-900-17137.80 ppb
2018-02-145810-903-162920.0 ppb
2018-02-145810-904-16469.40 ppb
2018-02-145810-905-17355.50 ppb
2018-05-155810-900-14356.20 ppb
2018-05-155810-901-160525.0 ppb
2018-05-155810-902-100912.0 ppb
2018-05-155810-903-15395.70 ppb
2018-05-155810-904-15055.80 ppb
2018-05-155810-905-13515.90 ppb
2018-05-155810-906-092664.0 ppb
2018-05-155810-907-141521.0 ppb
2018-08-145810-900-094013.0 ppb
2018-08-145810-901-113512.0 ppb
2018-08-145810-902-101011.0 ppb
2018-08-145810-903-112014.0 ppb
2018-08-145810-904-11007.70 ppb
2018-08-145810-905-090512.0 ppb
2018-08-145810-906-10305.90 ppb
2018-08-145810-907-092013.0 ppb
2018-11-155810-900-1305ND
2018-11-155810-901-1425ND
2018-11-155810-902-1120ND
2018-11-155810-903-14008.00 ppb
2018-11-155810-904-1335ND
2018-11-155810-905-1145ND
2018-11-155810-906-12304.60 ppb
2018-11-155810-907-1205ND
2019-02-125810-901-1625ND
2019-02-125810-902-124514.0 ppb
2019-02-125810-906-133513.0 ppb
2019-02-125810-907-122016.0 ppb
2019-02-135810-900-1032ND
2019-02-135810-903-094917.0 ppb
2019-02-135810-904-11467.60 ppb
2019-02-135810-905-105915.0 ppb
2019-05-145810-900-1516ND
2019-05-145810-901-142912.0 ppb
2019-05-145810-902-15396.20 ppb
2019-05-145810-903-140317.0 ppb
2019-05-145810-904-134315.0 ppb
2019-05-145810-905-145011.0 ppb
2019-05-145810-906-155615.0 ppb
2019-05-145810-907-15089.60 ppb
2019-08-135810-900-1211ND
2019-08-135810-901-1455ND
2019-08-135810-902-122713.0 ppb
2019-08-135810-903-142314.0 ppb
2019-08-135810-904-150611.0 ppb
2019-08-135810-905-11388.60 ppb
2019-08-135810-906-12415.40 ppb
2019-08-135810-907-120014.0 ppb
2019-11-145810-900-1352ND
2019-11-145810-901-1127ND
2019-11-145810-902-1248ND
2019-11-145810-903-1104ND
2019-11-145810-904-1030ND
2019-11-145810-905-1423ND
2019-11-145810-906-12337.40 ppb
2019-11-145810-907-1336ND