Our system was recently tested for the presence of Trihalomethanes (TTHM). What is TTHM? Total trihalomethanes (TTHM) are a group of disinfection byproducts that form when chlorine compounds that are used to disinfect water react with other naturally occurring chemicals in the water. They are colorless and will evaporate out of the water into the air. If these byproducts form in large enough quantities they can present health concerns, so the EPA has established a maximum contaminant of 80 parts per billion in drinking water. We are happy to say that there are no detectable levels of TTHM in the City of Ball Ground water supply.