Unlike chlorine, UV does not leave what in treated water?

Unlike chlorine, UV does not leave what in treated water?

• A. A Residual
• B. A Color
• C. A Taste
• D. A Turbidity

Answer: (A)

UV disinfection inactivates microorganisms by exposing them to UV light without adding any chemical to the water. Because nothing chemical is introduced, there is no residual disinfectant left in the treated water. That contrasts with chlorine, which remains as a disinfectant in the water after treatment and continues to provide protection as water moves through the distribution system. The lack of a residual with UV is why systems using UV often pair it with a separate residual method (like booster chlorination) to maintain disinfectant protection in the distribution system. UV itself won’t impart taste, color, or turbidity—those properties come from the water or other treatment steps, not from leaving a chemical residual behind.

UV disinfection inactivates microorganisms by exposing them to UV light without adding any chemical to the water. Because nothing chemical is introduced, there is no residual disinfectant left in the treated water. That contrasts with chlorine, which remains as a disinfectant in the water after treatment and continues to provide protection as water moves through the distribution system. The lack of a residual with UV is why systems using UV often pair it with a separate residual method (like booster chlorination) to maintain disinfectant protection in the distribution system. UV itself won’t impart taste, color, or turbidity—those properties come from the water or other treatment steps, not from leaving a chemical residual behind.