EWG's Tap Water Database — 2021 UPDATE


Haloacetic acids (HAA5)

Town of Apex

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.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
201414.8 ppb20209.10 ppb - 25.0 ppb
201525.2 ppb161612.0 ppb - 42.0 ppb
201621.4 ppb161615.0 ppb - 30.0 ppb
201721.8 ppb20209.50 ppb - 32.0 ppb
201816.9 ppb32326.00 ppb - 31.0 ppb
201913.9 ppb39397.70 ppb - 27.0 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
2014-02-1192189539001-29.70 ppb
2014-02-1192189539003-29.70 ppb
2014-02-1192189539004-29.10 ppb
2014-02-1192189539005-211.0 ppb
2014-05-1492201240001TTH-215.0 ppb
2014-05-1492201240002TTH-215.0 ppb
2014-05-1492201240003TTH-215.0 ppb
2014-05-1492201240004TTH-215.0 ppb
2014-05-1492201240001DIS-214.8 ppb
2014-05-1492201240002DIS-215.0 ppb
2014-05-1492201240003DIS-215.0 ppb
2014-05-1492201240004DIS-215.5 ppb
2014-08-1492213447001TTH-224.0 ppb
2014-08-1492213447002TTH-222.0 ppb
2014-08-1492213447003TTH-223.0 ppb
2014-08-1492213447004TTH-225.0 ppb
2014-11-1292225241001TTH-210.00 ppb
2014-11-1292225241002TTH-211.0 ppb
2014-11-1292225241003TTH-211.0 ppb
2014-11-1292225241004TTH-211.0 ppb
2015-02-1116.0 ppb
2015-02-1117.0 ppb
2015-02-1117.0 ppb
2015-02-1112.0 ppb
2015-05-1341.0 ppb
2015-05-1337.0 ppb
2015-05-1342.0 ppb
2015-05-1340.0 ppb
2015-08-1419.0 ppb
2015-08-1423.0 ppb
2015-08-1431.0 ppb
2015-08-1424.0 ppb
2015-11-1218.0 ppb
2015-11-1224.0 ppb
2015-11-1220.0 ppb
2015-11-1222.0 ppb
2016-02-1292286426001TTH-226.0 ppb
2016-02-1292286426003TTH-226.0 ppb
2016-02-1292286426004TTH-227.0 ppb
2016-02-1292286426005TTH-225.0 ppb
2016-05-1192297108001TTH-217.0 ppb
2016-05-1192297108003TTH-217.0 ppb
2016-05-1192297108004TTH-220.0 ppb
2016-05-1192297108005TTH-218.0 ppb
2016-08-1792309277001TTH-219.0 ppb
2016-08-1792309277002TTH-224.0 ppb
2016-08-1792309277003TTH-228.0 ppb
2016-08-1792309277004TTH-230.0 ppb
2016-11-1692319879001TTH-217.0 ppb
2016-11-1692319879002TTH-216.0 ppb
2016-11-1692319879004TTH-215.0 ppb
2016-11-1692319879005TTH-218.0 ppb
2017-02-1592329986001TTH22.0 ppb
2017-02-1592329986002TTH20.0 ppb
2017-02-1592329986004TTH17.0 ppb
2017-02-1592329986005TTH18.0 ppb
2017-05-1292340418001TTH23.0 ppb
2017-05-1292340418002TTH26.0 ppb
2017-05-1292340418004TTH22.0 ppb
2017-05-1292340418005TTH26.0 ppb
2017-08-1692351687001TTH31.0 ppb
2017-08-1692351687002TTH32.0 ppb
2017-08-1692351687003TTH31.0 ppb
2017-08-1692351687005TTH26.0 ppb
2017-11-1492363203001TTH13.0 ppb
2017-11-1492363203002TTH12.0 ppb
2017-11-1492363203003TTH28.0 ppb
2017-11-1492363203004TTH9.50 ppb
2017-11-1492363203005TTH27.0 ppb
2017-11-1492363203006TTH15.0 ppb
2017-11-1492363203007TTH17.0 ppb
2017-11-1492363203008TTH21.0 ppb
2018-02-1492373327001TTH 11.0 ppb
2018-02-1492373327002TTH 8.50 ppb
2018-02-1492373327003TTH 8.40 ppb
2018-02-1492373327004TTH 9.60 ppb
2018-02-1492373327005TTH 8.40 ppb
2018-02-1492373327006TTH 8.40 ppb
2018-02-1492373327007TTH 8.60 ppb
2018-02-1492373327008TTH 9.30 ppb
2018-05-1692384990001TTH 29.0 ppb
2018-05-1692384990002TTH 31.0 ppb
2018-05-1692384990003TTH 24.0 ppb
2018-05-1692384990004TTH 25.0 ppb
2018-05-1692384990005TTH 23.0 ppb
2018-05-1692384990006TTH 23.0 ppb
2018-05-1692384990007TTH 24.0 ppb
2018-05-1692384990008TTH 23.0 ppb
2018-08-1492395647001TTH 17.0 ppb
2018-08-1492395647002TTH 18.0 ppb
2018-08-1492395647003TTH 20.0 ppb
2018-08-1492395647004TTH 18.0 ppb
2018-08-1492395647005TTH 21.0 ppb
2018-08-1492395647006TTH 21.0 ppb
2018-08-1492395647007TTH 20.0 ppb
2018-08-1492395647008TTH 17.0 ppb
2018-11-1692407681001TTH 6.00 ppb
2018-11-1692407681002TTH 15.0 ppb
2018-11-1692407681003TTH 15.0 ppb
2018-11-1692407681004TTH 15.0 ppb
2018-11-1692407681005TTH 14.0 ppb
2018-11-1692407681006TTH 17.0 ppb
2018-11-1692407681007TTH 16.0 ppb
2018-11-1692407681008TTH 16.0 ppb
2019-02-1492417771001_377010.00 ppb
2019-02-1492417771001_377010.00 ppb
2019-02-1492417771002_377010.1 ppb
2019-02-1492417771002_377010.1 ppb
2019-02-1492417771004_37708.00 ppb
2019-02-1492417771004_37708.00 ppb
2019-02-1492417771005_377011.0 ppb
2019-02-1492417771005_377011.0 ppb
2019-02-1492417771006_377011.6 ppb
2019-02-1492417771006_377011.6 ppb
2019-02-1492417771007_377013.0 ppb
2019-02-1492417771007_377013.0 ppb
2019-02-1492417771008_37708.70 ppb
2019-02-1492417771009_37708.00 ppb
2019-02-1492417771009_37708.00 ppb
2019-05-1592429303001_377027.0 ppb
2019-05-1592429303002_377020.0 ppb
2019-05-1592429303003_377020.0 ppb
2019-05-1592429303004_377018.0 ppb
2019-05-1592429303005_377020.0 ppb
2019-05-1592429303006_377010.00 ppb
2019-05-1592429303007_377025.0 ppb
2019-05-3192431170001_377013.5 ppb
2019-09-2592446996002_377013.6 ppb
2019-09-2592446996003_377016.0 ppb
2019-09-2592446996004_377010.6 ppb
2019-09-2592446996005_377011.2 ppb
2019-09-2592446996006_377013.0 ppb
2019-09-2592446996007_377010.00 ppb
2019-09-2592446996008_377010.00 ppb
2019-09-2592446996009_37709.70 ppb
2019-11-1392453473001_37707.90 ppb
2019-11-1392453473002_377027.0 ppb
2019-11-1392453473003_377020.0 ppb
2019-11-1392453473004_37707.70 ppb
2019-11-1392453473005_37708.70 ppb
2019-11-1392453473006_377026.0 ppb
2019-11-1392453473007_377024.0 ppb
2019-11-1392453473008_377023.0 ppb