Know Your Environment. Protect Your Health.

Chloroform

Regional Water Authority

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.

 

376

Samples

0

Samples exceeding legal limit (MCL)

337

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
201842.9 ppb5853ND - 72.6 ppb
201928.2 ppb5953ND - 55.6 ppb
202027.5 ppb6055ND - 59.2 ppb
202125.3 ppb6055ND - 70.1 ppb
202229.5 ppb6056ND - 62.3 ppb
202319.6 ppb7965ND - 64.2 ppb

ppb = parts per billion

State, National, and Health Guidelines for Drinking Water

EWG Health Guideline: 0.4 ppb

The EWG Health Guideline of 0.4 ppb for chloroform was based on the California Office of Environmental Health Hazard Assessment's public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer and harm to fetal growth and development.

ppb = parts per billion

All test results

Date Lab ID Result
2018-03-05VOC1 200489156ND
2018-03-05VOC1 20048912813.7 ppb
2018-03-05VOC1 20048912919.0 ppb
2018-03-05VOC1 2004891509.00 ppb
2018-03-06DBP 20048926842.1 ppb
2018-03-06DBP 20048927543.7 ppb
2018-03-06DBP 20048928754.1 ppb
2018-03-06VOC1 200489295ND
2018-03-06VOC1 200489298ND
2018-03-06VOC1 200489296ND
2018-03-07DBP 20048953743.4 ppb
2018-03-07DBP 20048953852.3 ppb
2018-03-07DBP 20048953972.6 ppb
2018-03-07DBP 20048954057.8 ppb
2018-03-07DBP 20048954141.8 ppb
2018-03-08DBP 20048956530.6 ppb
2018-03-09DBP 20048970167.5 ppb
2018-03-09DBP 20048970270.9 ppb
2018-03-09DBP 20048970335.5 ppb
2018-06-05DBP 20049598443.0 ppb
2018-06-05DBP 20049598946.1 ppb
2018-06-05DBP 20049600258.3 ppb
2018-06-06DBP 20049623553.2 ppb
2018-06-07DBP 20049637535.4 ppb
2018-06-07DBP 20049637649.4 ppb
2018-06-07DBP 20049641737.4 ppb
2018-06-08DBP 20049650762.1 ppb
2018-06-08DBP 20049650839.5 ppb
2018-06-08DBP 20049650959.7 ppb
2018-06-08DBP 20049651059.4 ppb
2018-06-08DBP 20049651141.8 ppb
2018-08-17VOC1 20050273517.6 ppb
2018-09-04DBP 20050373252.6 ppb
2018-09-04DBP 20050373753.8 ppb
2018-09-04DBP 20050384259.8 ppb
2018-09-04DBP 20050391270.8 ppb
2018-09-04DBP 20050391371.0 ppb
2018-09-04DBP 20050391454.8 ppb
2018-09-05DBP 20050398166.7 ppb
2018-09-05DBP 20050408642.7 ppb
2018-09-05DBP 20050408743.9 ppb
2018-09-06DBP 20050418542.1 ppb
2018-09-06DBP 20050421157.2 ppb
2018-09-07DBP 20050444147.0 ppb
2018-11-29VOC1 200514106ND
2018-11-29VOC1 2005141211.000 ppb
2018-12-03DBP 20051437227.2 ppb
2018-12-03DBP 20051440641.8 ppb
2018-12-04DBP 20051444741.9 ppb
2018-12-04DBP 20051445249.8 ppb
2018-12-04DBP 20051462561.6 ppb
2018-12-04DBP 20051462665.5 ppb
2018-12-04DBP 20051462749.3 ppb
2018-12-04DBP 20051462839.4 ppb
2018-12-04DBP 20051462950.7 ppb
2018-12-05DBP 20051495251.3 ppb
2018-12-06DBP 20051506941.0 ppb
2018-12-06DBP 20051507049.8 ppb
2019-03-04DBP 20052321520.8 ppb
2019-03-04DBP 20052321726.6 ppb
2019-03-04VOC1 2005231506.60 ppb
2019-03-04VOC1 2005231516.80 ppb
2019-03-04VOC1 2005231756.90 ppb
2019-03-04VOC1 2005231761.20 ppb
2019-03-05DBP 20052326222.0 ppb
2019-03-05DBP 20052326925.5 ppb
2019-03-05DBP 20052345626.2 ppb
2019-03-05DBP 20052345736.4 ppb
2019-03-05DBP 20052345827.9 ppb
2019-03-05DBP 20052345924.8 ppb
2019-03-05DBP 20052346317.9 ppb
2019-03-05VOC1 200523251ND
2019-03-05VOC1 200523254ND
2019-03-05VOC1 200523252ND
2019-03-05VOC1 200523253ND
2019-03-05VOC1 2005232840.600 ppb
2019-03-05VOC1 200523286ND
2019-03-07DBP 20052388423.2 ppb
2019-03-08DBP 20052400019.9 ppb
2019-03-08DBP 20052400227.0 ppb
2019-05-08VOC1 200531298ND
2019-06-03DBP 20053437334.9 ppb
2019-06-03DBP 20053441437.1 ppb
2019-06-04DBP 20053449133.3 ppb
2019-06-04DBP 20053449635.3 ppb
2019-06-04DBP 20053460032.2 ppb
2019-06-04DBP 20053472541.3 ppb
2019-06-04DBP 20053472737.4 ppb
2019-06-04DBP 20053472944.4 ppb
2019-06-05DBP 20053503948.4 ppb
2019-06-05DBP 20053504134.7 ppb
2019-06-06DBP 20053519736.6 ppb
2019-06-07DBP 20053535741.4 ppb
2019-09-03DBP 20054698839.7 ppb
2019-09-03DBP 20054699345.9 ppb
2019-09-04DBP 20054740036.3 ppb
2019-09-04DBP 20054740247.1 ppb
2019-09-04DBP 20054740346.8 ppb
2019-09-04DBP 20054740441.7 ppb
2019-09-04DBP 20054740536.9 ppb
2019-09-05DBP 20054746050.7 ppb
2019-09-05DBP 20054766755.6 ppb
2019-09-06DBP 20054782642.4 ppb
2019-09-06DBP 20054782750.7 ppb
2019-09-06DBP 20054782841.4 ppb
2019-12-02DBP 20055840535.3 ppb
2019-12-02DBP 20055840628.8 ppb
2019-12-02DBP 20055840737.0 ppb
2019-12-03DBP 20055845425.9 ppb
2019-12-03DBP 20055845930.5 ppb
2019-12-03DBP 20055861230.6 ppb
2019-12-04DBP 20055891627.6 ppb
2019-12-04DBP 20055891730.1 ppb
2019-12-04DBP 20055891920.8 ppb
2019-12-05DBP 20055907332.5 ppb
2019-12-05DBP 20055909823.2 ppb
2019-12-06DBP 20055919528.6 ppb
2020-03-02DBP 20056771330.3 ppb
2020-03-02DBP 20056771444.8 ppb
2020-03-02DBP 20056771536.2 ppb
2020-03-02DBP 20056771826.8 ppb
2020-03-02VOC1 2005676648.70 ppb
2020-03-02VOC1 20056766511.0 ppb
2020-03-02VOC1 200567639A7.20 ppb
2020-03-02VOC1 2005676400.900 ppb
2020-03-02VOC1 2005676397.20 ppb
2020-03-03DBP 20056778028.2 ppb
2020-03-03DBP 20056778734.0 ppb
2020-03-03DBP 20056792026.7 ppb
2020-03-03DBP 20056792127.7 ppb
2020-03-03VOC1 200567761ND
2020-03-03VOC1 200567764ND
2020-03-03VOC1 200567762ND
2020-03-03VOC1 200567961ND
2020-03-04DBP 20056817730.1 ppb
2020-03-04DBP 20056817827.5 ppb
2020-03-05DBP 2005682851.30 ppb
2020-03-05DBP 20056838422.6 ppb
2020-03-05VOC1 200568299ND
2020-03-12DBP 20056916427.2 ppb
2020-06-01DBP 20057726432.1 ppb
2020-06-01DBP 20057726542.6 ppb
2020-06-01DBP 20057726638.2 ppb
2020-06-02DBP 20057731833.2 ppb
2020-06-02DBP 20057732724.9 ppb
2020-06-02DBP 20057739938.0 ppb
2020-06-02DBP 20057740125.4 ppb
2020-06-03DBP 20057771928.3 ppb
2020-06-03DBP 20057772136.1 ppb
2020-06-04DBP 20057795428.4 ppb
2020-06-04DBP 20057795529.7 ppb
2020-06-05DBP 20057807724.6 ppb
2020-09-08DBP 20058910957.0 ppb
2020-09-08DBP 20058911848.9 ppb
2020-09-08DBP 20058925259.2 ppb
2020-09-08DBP 20058925353.2 ppb
2020-09-08DBP 20058925447.8 ppb
2020-09-09DBP 20058956039.7 ppb
2020-09-09DBP 20058956145.6 ppb
2020-09-10DBP 20058979742.3 ppb
2020-09-10DBP 20058979929.1 ppb
2020-09-10DBP 20058980350.8 ppb
2020-09-10DBP 20058980636.9 ppb
2020-09-11DBP 20058986841.8 ppb
2020-12-07DBP 20060013631.8 ppb
2020-12-07DBP 20060013729.3 ppb
2020-12-08DBP 20060032623.1 ppb
2020-12-08DBP 20060040724.9 ppb
2020-12-08DBP 20060040828.1 ppb
2020-12-09DBP 20060056219.7 ppb
2020-12-09DBP 20060060717.7 ppb
2020-12-09DBP 20060065326.6 ppb
2020-12-09DBP 20060065629.5 ppb
2020-12-10DBP 20060088228.4 ppb
2020-12-10DBP 20060088418.7 ppb
2020-12-10DBP 200600884B18.7 ppb
2020-12-11DBP 20060095423.1 ppb
2021-03-08DBP 20060880921.0 ppb
2021-03-08DBP 20060883519.3 ppb
2021-03-08DBP 20060883623.5 ppb
2021-03-08DBP 20060883718.8 ppb
2021-03-08VOC1 2006088016.50 ppb
2021-03-08VOC1 20060888510.4 ppb
2021-03-08VOC1 2006088820.800 ppb
2021-03-09DBP 20060891419.1 ppb
2021-03-09DBP 20060908927.2 ppb
2021-03-09DBP 20060909015.2 ppb
2021-03-09DBP 20060909318.4 ppb
2021-03-09VOC1 200608962ND
2021-03-09VOC1 200608960ND
2021-03-09VOC1 200608959ND
2021-03-09VOC1 200608951ND
2021-03-09VOC1 2006089249.10 ppb
2021-03-09VOC1 2006089860.600 ppb
2021-03-10DBP 20060925119.4 ppb
2021-03-10DBP 20060925218.2 ppb
2021-03-10VOC1 200609193ND
2021-03-11DBP 2006094201.90 ppb
2021-03-11DBP 20060951222.7 ppb
2021-03-12DBP 20060958422.2 ppb
2021-06-07DBP 20061968030.3 ppb
2021-06-07DBP 20061967835.8 ppb
2021-06-07DBP 20061967941.1 ppb
2021-06-08DBP 20061980033.4 ppb
2021-06-08DBP 20061980235.3 ppb
2021-06-08DBP 20061992041.5 ppb
2021-06-08DBP 20061992124.4 ppb
2021-06-08DBP 20061992220.7 ppb
2021-06-09DBP 20062017334.4 ppb
2021-06-10DBP 20062049326.8 ppb
2021-06-10DBP 20062049522.1 ppb
2021-06-11DBP 20062058320.9 ppb
2021-09-13300057530 30005753246.3 ppb
2021-09-13300057533 30005753558.8 ppb
2021-09-13300057536 30005753870.1 ppb
2021-09-14300058253 30005825743.3 ppb
2021-09-14300058258 30005826254.7 ppb
2021-09-14300059322 30005932639.6 ppb
2021-09-14300059327 30005932939.6 ppb
2021-09-14300059398 30005940026.6 ppb
2021-09-14V300058206 3000588760.600 ppb
2021-09-15300060630 30006063249.3 ppb
2021-09-16300061467 30006146945.0 ppb
2021-09-16300061470 30006147239.5 ppb
2021-09-17300062097 30006209941.6 ppb
2021-12-13D300117139 30011714128.6 ppb
2021-12-13D300117142 30011714432.1 ppb
2021-12-13D300117145 30011714729.0 ppb
2021-12-13D300117148 30011715034.4 ppb
2021-12-13D300118224 30011822815.1 ppb
2021-12-13D300118229 30011823123.5 ppb
2021-12-14D300117272 30011727625.6 ppb
2021-12-14D300117277 30011728132.6 ppb
2021-12-15D300119211 30011921321.5 ppb
2021-12-16D300120051 30012005331.0 ppb
2021-12-16D300120054 30012005627.5 ppb
2021-12-17D300120678 30012068023.6 ppb
2022-03-07D300153474 30015347630.0 ppb
2022-03-07D300153477 30015347936.1 ppb
2022-03-07D300153480 30015348227.1 ppb
2022-03-07V300153323 3001533296.50 ppb
2022-03-07V300153337 3001533439.20 ppb
2022-03-07V300153401 3001534078.80 ppb
2022-03-07V300153384 3001533903.30 ppb
2022-03-08D300153988 30015399228.0 ppb
2022-03-08D300153993 30015399732.5 ppb
2022-03-08D300154252 30015425622.0 ppb
2022-03-08D300154257 30015425928.8 ppb
2022-03-08D300154260 30015426221.0 ppb
2022-03-08V300153972 300153978ND
2022-03-08V300153964 300153970ND
2022-03-08V300153956 3001539620.800 ppb
2022-03-08V300154039 3001540440.700 ppb
2022-03-08V300154049 3001540540.600 ppb
2022-03-09D300155008 30015501024.8 ppb
2022-03-09V300154647 300154653ND
2022-03-09V300154596 300154602ND
2022-03-10D300155239 3001552431.10 ppb
2022-03-10D300155826 30015582930.9 ppb
2022-03-10D300155831 30015583438.3 ppb
2022-03-11D300156650 30015665222.4 ppb
2022-06-06D300193482 30019348641.2 ppb
2022-06-06D300193487 30019349046.5 ppb
2022-06-06D300193491 30019349456.4 ppb
2022-06-06D300193495 30019349836.3 ppb
2022-06-07D300194485 30019448826.4 ppb
2022-06-07D300194421 30019442543.3 ppb
2022-06-07D300194474 30019447839.2 ppb
2022-06-08D300194960 30019496339.8 ppb
2022-06-08D300196206 30019620940.7 ppb
2022-06-08D300196210 30019621362.3 ppb
2022-06-08D300196214 30019621755.3 ppb
2022-06-10D300196552 30019655537.9 ppb
2022-09-12D300242309 30024231257.3 ppb
2022-09-12D300242313 30024231646.0 ppb
2022-09-13D300242867 30024287144.8 ppb
2022-09-13D300242872 30024287645.4 ppb
2022-09-13D300243354 30024335841.4 ppb
2022-09-13D300243359 30024336231.0 ppb
2022-09-14D300243943 30024394644.6 ppb
2022-09-14D300243947 30024395055.8 ppb
2022-09-14D300243951 30024395445.4 ppb
2022-09-15D300244400 30024440330.1 ppb
2022-09-15D300244404 30024440730.7 ppb
2022-09-15D300245400 30024540338.9 ppb
2022-12-05D300280513 30028051628.6 ppb
2022-12-05D300280517 30028052040.4 ppb
2022-12-05D300280521 30028052433.0 ppb
2022-12-06D300281387 30028139127.9 ppb
2022-12-06D300281392 30028139539.4 ppb
2022-12-06D300281396 30028139920.6 ppb
2022-12-07D300282133 30028213727.6 ppb
2022-12-07D300282138 30028214232.0 ppb
2022-12-07D300282730 30028273339.3 ppb
2022-12-08D300283547 30028355023.2 ppb
2022-12-08D300283566 30028356926.4 ppb
2022-12-09D300284348 30028435120.9 ppb
2023-02-06V300305519 300305525ND
2023-02-21V300312034 3003124896.90 ppb
2023-02-21V300312044 3003124918.90 ppb
2023-02-21V300312000 30031226910.9 ppb
2023-02-21V300312008 3003122710.900 ppb
2023-03-06D300316509 30031651221.3 ppb
2023-03-06D300316513 30031651627.1 ppb
2023-03-06D300316517 30031652017.3 ppb
2023-03-06V300316290 3003162965.90 ppb
2023-03-06V300316304 3003163108.20 ppb
2023-03-06V300316337 3003163437.50 ppb
2023-03-06V300316298 300316301ND
2023-03-06V300316312 300316315ND
2023-03-06V300316345 300316348ND
2023-03-07D300317097 30031710118.0 ppb
2023-03-07D300317102 30031710619.3 ppb
2023-03-07D300317505 30031750917.2 ppb
2023-03-07D300317510 30031751320.6 ppb
2023-03-07D300317514 30031751714.1 ppb
2023-03-07V300316907 300316913ND
2023-03-07V300316899 300316905ND
2023-03-07V300317611 3003176171.10 ppb
2023-03-07V300317619 3003176220.600 ppb
2023-03-08D300318389 30031839216.4 ppb
2023-03-08D300318393 30031839618.6 ppb
2023-03-08V300318416 300318422ND
2023-03-08V300317948 3003179530.800 ppb
2023-03-08V300317958 3003179631.80 ppb
2023-03-09D300319243 30031924625.8 ppb
2023-03-09V300319225 300319231ND
2023-03-10D300319398 30031940124.4 ppb
2023-06-05D300358943 30035894624.1 ppb
2023-06-05D300358947 30035895031.6 ppb
2023-06-05D300358951 30035895425.7 ppb
2023-06-05D300358955 30035895822.8 ppb
2023-06-05V300358561 300358568ND
2023-06-06D300358988 30035899221.3 ppb
2023-06-06D300358993 30035899729.1 ppb
2023-06-06D300359847 30035985150.8 ppb
2023-06-06D300359852 30035985540.5 ppb
2023-06-06V300359376 300359383ND
2023-06-06V300359368 300359375ND
2023-06-06V300359360 300359367ND
2023-06-06V300359352 300359359ND
2023-06-06V300359024 3003590316.60 ppb
2023-06-06V300359033 30035904031.2 ppb
2023-06-06V300359384 30035939117.6 ppb
2023-06-06V300359393 3003594002.00 ppb
2023-06-07D300360865 30036086831.9 ppb
2023-06-07V300360413 3003604200.700 ppb
2023-06-07V300360421 300360428ND
2023-06-08D300361983 30036198627.7 ppb
2023-06-08D300361987 30036199035.2 ppb
2023-06-09D300362721 30036272427.7 ppb
2023-06-28D300372809 30037341529.8 ppb
2023-09-11D300412854 30041285760.0 ppb
2023-09-11D300412858 30041286137.2 ppb
2023-09-12D300413093 30041309737.3 ppb
2023-09-12D300413098 30041310247.6 ppb
2023-09-12D300413568 30041357254.4 ppb
2023-09-12D300413573 30041357643.8 ppb
2023-09-12D300413577 30041358042.9 ppb
2023-09-12D300413581 30041358446.3 ppb
2023-09-13D300414470 30041447332.3 ppb
2023-09-13D300414474 30041447733.4 ppb
2023-09-14D300415299 30041530245.5 ppb
2023-09-15D300416083 30041608664.2 ppb
2023-12-04D300454311 30045431419.7 ppb
2023-12-04D300454315 30045431827.9 ppb
2023-12-04D300454322 30045432522.6 ppb
2023-12-05D300454448 30045445217.7 ppb
2023-12-05D300454453 30045445721.5 ppb
2023-12-05D300454954 30045495825.6 ppb
2023-12-05D300454962 30045496518.8 ppb
2023-12-05D300454972 30045497524.5 ppb
2023-12-06D300455828 30045583112.1 ppb
2023-12-06D300455832 30045583513.5 ppb
2023-12-07D300456845 30045684821.8 ppb
2023-12-08D300457513 30045751626.2 ppb