Disinfection Byproducts are formed when disinfectants react with what in water?

• A. They are formed when disinfectants react with natural organic matter
• B. They are formed when disinfectants react with inorganic minerals
• C. They are formed when microorganisms are absent
• D. They are formed only in the absence of disinfectants

Answer: (A)

Disinfection byproducts are produced when disinfectants react with natural organic matter in the water. Natural organic matter, from decaying vegetation and other sources in source waters, contains reactive organic structures. When chlorine or other disinfectants are added for disinfection, these organics react and halogens become incorporated into the molecules, forming byproducts such as trihalomethanes and haloacetic acids. Without this natural organic matter, DBP formation is much less likely; inorganic minerals aren’t the primary precursors, and the presence or absence of microorganisms doesn’t drive the formation.