The following conditions should be guaranteed: the pH of the water should be low, generally around 7 to reduce the dissociation of hypochlorous acid, because the hypochlorite (OCl-) is negatively charged and it is not easy to play a disinfection effect; the water quality should be transparent.
In order to facilitate the contact of hypochlorous acid with pathogens; the water temperature should not be too low, and the high water temperature will have a faster sterilization ability. Therefore, the amount of chlorine added should be increased or decreased according to the water temperature, so that the added chlorine is fully mixed, and there is a certain contact reaction time (generally not less than 30 minutes); after 30 minutes of contact, it is required that the free residual chlorine content of the water in the pipe network near the water plant or pressurized station should not be less than 0.3mg/L, and the free residual chlorine in the water in the terminal pipe network should not be Should be less than 0.05mg/L.
The bacteriological indicators in the water after disinfection can be detected to evaluate the disinfection effect. The total number of bacteria (24 hours at 37°C) should not exceed 100/ml water, and the number of coliforms should not exceed 3 per liter of water. In areas with a long water distribution network and many dead ends, in order to ensure the safety of drinking water quality, chlorination should be considered midway.