Episodic Trihalomethane Species and Levels in Tap Water at a Start of Operation of Advanced Treatment in Osaka Prefectural Water Supplies

Empirical equations for explaining trihalomethane (THM) distribution were established based on data on tap water in Osaka City before and after starting the advanced treatment and were represented by the following equations for bromodichloromethane (S₁), dibromochloromethane (S₂) and bromoform distribution factors (S₃) as a function of chloroform distribution factor (S₀), respectively: S₁ = −0.97S₀² + 0.75S₀ + 0.19 (regression coefficient: r = 0.71), S₂ = 0.13S₀²−0.76S₀ + 0.51 (r = 0.98) and S₃ = 0.83S₀²−0.99S₀ + 0.30 (r = 0.97). Further, the derived equations were verified by THMs data of Osaka Prefecture and its surrounding cities (except for Osaka City), receiving a combination of advanced treated water and conventionally treated different source water.