The part of a water treatment plant where effluent is disinfected by chlorine. The Chlorine Contact Chamber is the last treatment process when it is required before the water is released into the water supply. Chlorine is dosed into the tank and allowed some time to eradicate the remaining bacteria and viruses. Once this process is complete, then the water is purified with sulfur dioxide to eliminate the chlorine. This two-step process is necessary for the release of clean water into the water supply for the safety of aquatic life. Many plants are becoming increasingly reliant on ultraviolet disinfection due to its safety and productivity in utilizing chlorine.