Which regulation requires surface water systems to maintain specific C x T values?

• A. Clean Water Act
• B. Surface Water Treatment Rule (SWTR)
• C. Safe Drinking Water Act
• D. National Pollutant Discharge Elimination System (NPDES)

Answer: (B)

The Surface Water Treatment Rule (SWTR) is the regulation that mandates surface water systems to maintain specific C x T values. The C x T value represents the contact time (T) multiplied by the concentration of the disinfectant (C) used in the treatment process. This value is critical because it ensures that the disinfection process is adequate to inactivate pathogens in the water, thus protecting public health.

The significance of C x T values lies in their role in providing a quantitative measure that determines the effectiveness of disinfection. By adhering to the requirements set forth in the SWTR, surface water systems can demonstrate that they are effectively managing the risk of waterborne diseases through appropriate treatment protocols.

The other regulations listed do not specifically set forth C x T requirements for surface water treatment. The Clean Water Act focuses on regulating discharges into waters of the United States to maintain and restore the quality of those waters, while the Safe Drinking Water Act provides overarching guidelines for safe drinking water but does not specifically address C x T values like the SWTR does. The National Pollutant Discharge Elimination System (NPDES) deals with permits for point source discharges and does not encompass treatment performance standards for disinfection in surface water systems.