CT stands for Concentration and Time. As soon as a disinfectant is added to water it begins the disinfection process. What is the concentration of the disinfectant and how long is it in contact with the water? It takes “time” to complete the disinfection process. In addition, there are other variables that can delay the disinfection process such as, pH, water temperature, turbidity, and the amount of pathogens in the water among other things. Therefore, knowing the CT (concentration of the disinfectant and the time the disinfectant has to do its “work”) is very important in ensuring that the water is properly disinfected and safe for human consumption.