Contact time

Contact time is the product of the residual concentration of disinfectant (C), measured in mg/L at the outlet of the contact chamber, and the disinfectant contact time (T), measured in minutes. Contact time is increased when either the disinfectant concentration or the disinfectant contact time are increased, indicating a higher level of disinfection. The CT values required to achieve the necessary inactivation will depend on the microorganism targeted, pH, and temperature.