THMs and HAAs in New England Water

Trihalomethanes (THMs) and Haloacetic acids (HAAs)

The U.S. Environmental Protection Agency (EPA) regulations offer two options for disinfectant residuals in public water supplies as they travel through distribution systems: chlorine or chloramine (a combination of chlorine and ammonia). Chlorine can produce byproducts like trihalomethanes (THMs) and haloacetic acids (HAAs) when introduced to water with organic matter, which is common in surface water sources. Chloramine produces fewer THMs and HAAs but has other issues. Many major water agencies are switching to chloramine to meet current and anticipated federal drinking water regulations.

Chloramine lasts longer in distribution systems than chlorine, requiring less for the residual to reach the last house on the distribution system. This can eliminate the problem of high dosage requirements affecting homes at the front of the distribution system with an objectionable end product. While "chloramine" is commonly used, the actual compound used is monochloramine, which is different from dichloramine and trichloramine, formed by other complex chemical reactions. Dichloramine and trichloramine are sometimes found in indoor swimming pools and can cause skin, eye, and respiratory problems.

Health Effects of THMS and HAAS in Household Water

Drinking water research indicates that certain DBPs have the potential to be harmful. Some research indicates a link to an increase in cancer incidence, including bladder cancer. Liver, kidney, and central nervous system problems, along with reproductive effects, have also been noted. Scientists from many organizations have conducted research on the effects of DBPs, with some studies showing links to adverse health effects and others not. EPA sets limits for certain DBPs linked to the health effects previously described. 

Exposure to THMs can occur from drinking tap water containing the chemical compounds as well as showering, bathing, and other water use activities contributing to an individual's total exposure. THMs can evaporate from the tap and be inhaled during showering or be absorbed through the skin during bathing. To remove THMs from your water supply in your home or business, the installation of a system containing activated carbon is the most effective and practical approach. The carbon is able to essentially trap the THMs until reaching maximum absorption. The carbon media inside the tank should be exchanged at regular intervals established by you and your water treatment professional.

If your town uses chloramine instead of chlorine, it can still be removed before it enters your home. Because the chloramine conversion reaction is catalytic in nature, activated carbons that exhibit enhanced catalytic activity are more efficient.  The chloramine removal efficiencies of catalytic carbons cut required contact time, extend bed life, and enable the use of smaller equipment. These advantages translate into cost savings for the end user without the sacrifice of the carbon's capabilities.