What condition can lead to increased formation of Total Trihalomethanes (TTHMs)?

The formation of Total Trihalomethanes (TTHMs) in drinking water is significantly influenced by the pH level of the water. A high pH level can lead to increased formation of TTHMs because it enhances the reactivity of chlorine with organic matter present in the water. When chlorine is used as a disinfectant, it reacts with natural organic materials, and this reaction is more pronounced at higher pH levels, resulting in a greater yield of trihalomethanes.

At low pH levels, the chlorine's effectiveness as a disinfectant may diminish, and the reaction with organic precursors may produce fewer TTHMs. Therefore, managing the pH within an appropriate range is important for controlling TTHM levels in treated water. High chlorination practices can also lead to TTHM formation, but the key condition specifically for increased formation is associated with high pH.