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EWG's Tap Water Database — 2021 UPDATE

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Chloroform

California Water Service (CWS) - Los Altos Suburban

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.

MORE ABOUT THIS CONTAMINANT

 

270

Samples

0

Samples exceeding legal limit (MCL)

163

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2013N/A00N/A
20141.70 ppb4826ND - 30.4 ppb
20152.54 ppb4721ND - 11.7 ppb
20164.62 ppb3931ND - 12.0 ppb
20175.99 ppb4327ND - 26.0 ppb
20183.56 ppb4627ND - 14.0 ppb
20192.94 ppb4731ND - 13.0 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
2014-02-055701-024-1427ND
2014-02-135701-900-12050.560 ppb
2014-02-135701-901-1322ND
2014-02-135701-902-11080.510 ppb
2014-02-135701-903-13441.71 ppb
2014-02-135701-904-13061.45 ppb
2014-02-135701-905-12410.700 ppb
2014-02-135701-906-1150ND
2014-02-135701-907-1132ND
2014-02-265701-002-1423ND
2014-02-265701-010-1456ND
2014-02-265701-018-1055ND
2014-03-255701-011-1305ND
2014-03-255701-028-1530ND
2014-03-255701-030-1555ND
2014-04-081610-903-085030.4 ppb
2014-04-225701-020-1340ND
2014-04-225701-021-1140ND
2014-04-225701-022-1238ND
2014-05-155701-900-13342.46 ppb
2014-05-155701-901-1433ND
2014-05-155701-902-12292.83 ppb
2014-05-155701-903-14574.27 ppb
2014-05-155701-904-14061.73 ppb
2014-05-155701-905-13482.56 ppb
2014-05-155701-906-13082.70 ppb
2014-05-155701-907-12463.90 ppb
2014-06-245701-028-0945ND
2014-07-225701-024-0923ND
2014-08-075701-900-12302.30 ppb
2014-08-075701-901-1337ND
2014-08-075701-902-11432.02 ppb
2014-08-075701-903-14052.61 ppb
2014-08-075701-904-14312.19 ppb
2014-08-075701-905-12482.33 ppb
2014-08-075701-906-12062.48 ppb
2014-08-075701-907-11132.26 ppb
2014-09-245701-028-1050ND
2014-10-215701-024-1545ND
2014-11-125701-900-13130.690 ppb
2014-11-125701-901-1433ND
2014-11-125701-902-10401.23 ppb
2014-11-125701-903-13552.88 ppb
2014-11-125701-904-1330ND
2014-11-125701-905-12501.20 ppb
2014-11-125701-906-12181.04 ppb
2014-11-125701-907-11422.80 ppb
2014-12-165701-028-1230ND
2015-01-215701-024-0905ND
2015-02-095701-900-0802ND
2015-02-095701-901-0802ND
2015-02-095701-902-0802ND
2015-02-095701-903-08021.79 ppb
2015-02-095701-904-0802ND
2015-02-095701-905-0802ND
2015-02-095701-906-0802ND
2015-02-095701-907-08022.92 ppb
2015-02-185701-002-1340ND
2015-02-185701-013-1145ND
2015-02-185701-016-0950ND
2015-02-185701-018-1315ND
2015-03-185701-028-1100ND
2015-04-215701-024-1025ND
2015-05-145701-900-084710.3 ppb
2015-05-145701-901-084710.5 ppb
2015-05-145701-902-08479.01 ppb
2015-05-145701-903-084711.7 ppb
2015-05-145701-904-084710.00 ppb
2015-05-145701-905-08479.42 ppb
2015-05-145701-906-084711.3 ppb
2015-05-145701-907-08477.70 ppb
2015-06-165701-028-1117ND
2015-07-205701-024-1145ND
2015-07-205701-029-1125ND
2015-08-115701-900-09384.04 ppb
2015-08-115701-901-09383.88 ppb
2015-08-115701-902-09383.98 ppb
2015-08-115701-903-09384.21 ppb
2015-08-115701-904-09383.66 ppb
2015-08-115701-905-09384.10 ppb
2015-08-115701-906-09383.92 ppb
2015-08-115701-907-09383.30 ppb
2015-08-245701-023-1130ND
2015-09-225701-028-1100ND
2015-09-225701-057-1130ND
2015-11-095810-900-1232ND
2015-11-095810-901-1053ND
2015-11-095810-902-1132ND
2015-11-095810-903-10351.30 ppb
2015-11-095810-904-11141.20 ppb
2015-11-095810-905-1435ND
2015-11-095810-906-13211.10 ppb
2015-11-095810-907-1256ND
2015-12-105701-008-1525ND
2015-12-175701-028-1115ND
2016-02-095701-900-09133.21 ppb
2016-02-095701-901-0913ND
2016-02-095701-902-09132.78 ppb
2016-02-095701-903-091310.9 ppb
2016-02-095701-904-09138.42 ppb
2016-02-095701-905-09132.82 ppb
2016-02-095701-906-09132.25 ppb
2016-02-095701-907-09131.98 ppb
2016-03-215701-028-0952ND
2016-05-105810-901-130710.00 ppb
2016-05-105810-902-114712.0 ppb
2016-05-105810-906-12078.90 ppb
2016-05-105810-907-12329.30 ppb
2016-05-115810-900-12159.80 ppb
2016-05-115810-903-115012.0 ppb
2016-05-115810-904-11279.70 ppb
2016-05-115810-905-124711.0 ppb
2016-06-015701-028-1014ND
2016-07-265701-037-1320ND
2016-08-095701-900-09316.19 ppb
2016-08-095701-901-09316.06 ppb
2016-08-095701-902-09315.35 ppb
2016-08-095701-903-09316.15 ppb
2016-08-095701-904-09317.05 ppb
2016-08-095701-905-09315.92 ppb
2016-08-095701-906-09315.77 ppb
2016-08-095701-907-09315.91 ppb
2016-09-215701-028-1046ND
2016-09-215701-032-11463.43 ppb
2016-09-215701-035-1130ND
2016-11-155701-900-08511.63 ppb
2016-11-155701-901-0851ND
2016-11-155701-902-08511.92 ppb
2016-11-155701-903-08512.95 ppb
2016-11-155701-904-08511.69 ppb
2016-11-155701-905-08511.82 ppb
2016-11-155701-906-08511.81 ppb
2016-11-155701-907-08511.57 ppb
2016-12-135810-028-1140ND
2017-01-185701-010-1045ND
2017-01-185701-011-1123ND
2017-02-145701-020-1546ND
2017-02-145701-021-1624ND
2017-02-145810-900-13201.000 ppb
2017-02-145810-901-1205ND
2017-02-145701-902-11111.79 ppb
2017-02-145810-903-12406.90 ppb
2017-02-145810-904-13012.00 ppb
2017-02-145810-905-1345ND
2017-02-145810-906-15352.20 ppb
2017-02-145701-907-11111.66 ppb
2017-03-065701-022-1038ND
2017-03-155701-028-1234ND
2017-03-155701-030-1245ND
2017-05-095701-901-0908ND
2017-05-095701-902-090813.5 ppb
2017-05-095701-903-090826.0 ppb
2017-05-095701-904-090823.0 ppb
2017-05-095701-905-090824.2 ppb
2017-05-095701-906-090815.5 ppb
2017-05-095701-907-090825.4 ppb
2017-05-115701-900-153117.7 ppb
2017-06-265701-028-1420ND
2017-08-175810-900-13106.60 ppb
2017-08-175810-901-1135ND
2017-08-175810-902-13367.30 ppb
2017-08-175810-903-11117.50 ppb
2017-08-175810-904-12026.20 ppb
2017-08-175810-905-12266.00 ppb
2017-08-175810-906-14005.80 ppb
2017-08-175810-907-12476.90 ppb
2017-08-235701-022-1315ND
2017-09-265701-028-1430ND
2017-11-145810-900-13285.40 ppb
2017-11-145810-901-1211ND
2017-11-145810-902-135512.0 ppb
2017-11-145810-903-115016.0 ppb
2017-11-145810-904-12283.90 ppb
2017-11-145810-905-10024.50 ppb
2017-11-145810-906-14124.40 ppb
2017-11-145810-907-13074.30 ppb
2017-12-135701-028-1520ND
2018-02-135810-901-1131ND
2018-02-135810-902-13211.30 ppb
2018-02-135810-906-12591.90 ppb
2018-02-135810-907-14255.20 ppb
2018-02-145810-900-17134.00 ppb
2018-02-145810-903-16299.30 ppb
2018-02-145810-904-16465.60 ppb
2018-02-145810-905-17353.60 ppb
2018-02-205701-013-1225ND
2018-02-205701-018-1215ND
2018-03-215701-016-1245ND
2018-03-215701-028-1350ND
2018-05-085701-023-1310ND
2018-05-155810-900-14358.40 ppb
2018-05-155701-901-0947ND
2018-05-155701-902-09478.13 ppb
2018-05-155810-903-153911.0 ppb
2018-05-155810-904-150514.0 ppb
2018-05-155810-905-13518.60 ppb
2018-05-155701-906-09478.21 ppb
2018-05-155701-907-0947ND
2018-06-215701-024-0930ND
2018-06-215701-028-1131ND
2018-07-185701-029-0900ND
2018-08-145701-900-10166.84 ppb
2018-08-145701-901-10166.53 ppb
2018-08-145701-902-10166.19 ppb
2018-08-145701-903-10167.97 ppb
2018-08-145701-904-10168.05 ppb
2018-08-145701-905-10167.45 ppb
2018-08-145701-906-10166.78 ppb
2018-08-145701-907-10167.45 ppb
2018-09-065701-057-0757ND
2018-09-185701-057-1305ND
2018-09-245701-028-1200ND
2018-11-155701-900-0817ND
2018-11-155701-901-0817ND
2018-11-155701-902-08170.820 ppb
2018-11-155701-903-08177.12 ppb
2018-11-155701-904-08172.60 ppb
2018-11-155701-905-08171.26 ppb
2018-11-155701-906-08174.34 ppb
2018-11-155701-907-08170.960 ppb
2018-12-129590-002-1400ND
2018-12-125810-008-1117ND
2018-12-125810-028-1535ND
2019-02-125810-901-1625ND
2019-02-125810-902-124512.0 ppb
2019-02-125810-906-133510.00 ppb
2019-02-125810-907-122013.0 ppb
2019-02-135810-900-1036ND
2019-02-135810-903-09526.60 ppb
2019-02-135810-904-11504.80 ppb
2019-02-135810-905-110411.0 ppb
2019-02-205701-002-1245ND
2019-03-195810-028-1400ND
2019-05-145701-900-09360.830 ppb
2019-05-145701-901-09365.21 ppb
2019-05-145701-902-09362.30 ppb
2019-05-145701-903-09365.90 ppb
2019-05-145701-904-09364.63 ppb
2019-05-145701-905-09363.11 ppb
2019-05-145701-906-09364.59 ppb
2019-05-145701-907-09362.97 ppb
2019-06-185701-028-1510ND
2019-07-115701-024-11300.520 ppb
2019-07-245701-024-18001.06 ppb
2019-07-295701-024-15300.860 ppb
2019-08-065701-024-11450.600 ppb
2019-08-135701-024-11250.650 ppb
2019-08-135701-900-12131.91 ppb
2019-08-135701-901-1453ND
2019-08-135701-902-12254.87 ppb
2019-08-135701-903-14208.60 ppb
2019-08-135701-904-15094.49 ppb
2019-08-135701-905-11354.12 ppb
2019-08-135701-906-12394.56 ppb
2019-08-135701-907-11574.79 ppb
2019-08-195701-024-13250.650 ppb
2019-08-205810-037-1115ND
2019-08-265810-024-1355ND
2019-09-175701-028-1520ND
2019-09-175701-032-1530ND
2019-09-175701-035-1540ND
2019-11-145701-900-13521.96 ppb
2019-11-145701-901-1127ND
2019-11-145701-902-12481.10 ppb
2019-11-145701-903-1104ND
2019-11-145701-904-1030ND
2019-11-145701-905-1423ND
2019-11-145701-906-12339.39 ppb
2019-11-145701-907-13361.18 ppb
2019-12-165701-028-1330ND