Trihalomethanes are formed as a by-product predominantly when chlorine is used to disinfect drinking water. They are generally referred to as disinfection by-products. They result from the reaction of chlorine or bromine with organic matter present in the water being treated. The THMs produced have been associated through epidemiological studies with some adverse health effects. Many governments set limits on the amount permissible in drinking water. However, trihalomethanes are only one group of many hundreds of possible disinfection by-products—the vast majority of which are not monitored—and it has not yet been clearly demonstrated which of these are the most plausible candidate for causation of these health effects. In the United States, the EPA limits the total concentration of the four chief constituents (chloroform, bromoform, bromodichloromethane, and dibromochloromethane), referred to as total trihalomethanes (TTHM), to 80 parts per billion in treated water.
One of the easiest ways of eliminating the THMs in the water is through the use of an activated carbon filter. Our ClearChoice brand of fridge filters and drop-in carbon filters all utilize an activated carbon filter media, so they are an excellent choice for removing THMs and TTHMs from drinking water supplies