What do organics in surface water combine with to form trihalomethanes?

Trihalomethanes are formed when organic matter present in surface water reacts with chlorine, which is commonly added to municipal water supplies for disinfection. While halogens, such as chlorine, bromine, and iodine, can participate in these reactions, it's specifically the chlorine that is primarily responsible for the formation of trihalomethanes, primarily when it combines with the organic materials.

The presence of halogens in general does suggest they can also play a role, but in the context of water treatment and the formation of trihalomethanes, chlorine is the most significant halogen involved. Therefore, it's essential to recognize that while other halogens exist, it's the reaction with chlorine in the treatment process that leads to the formation of trihalomethanes specifically.

The focus on halogens is somewhat broader, as it encompasses all elements in Group 17 of the periodic table, but in typical scenarios involving disinfection of drinking water, chlorine is the primary agent that reacts with organic compounds to create trihalomethanes. Understanding this relationship is crucial for water treatment professionals concerned with the implications of disinfection byproducts in public health.