What type of chlorine should I use for wastewater disinfection?
Before any attempt is made to add chlorine to an aerobic septic system or tank, please read the following from the Texas Commission on Environmental Quality:
When disinfection of secondarily treated wastewater effluent is required and you are using chlorine tablets, it is important that you use a chlorine tablet that is made from calcium hypochlorite and is certified for wastewater disinfection by EPA. They are very reactive and will kill 99% of the bacteria present in the effluent within 10 minutes. Follow all warning and precaution statements of the chlorine tablet manufacturer to protect yourself and the system equipment.
WARNING: DO NOT use swimming pool chlorine tablets in your disinfection system. The chlorine in these tablets are made from trichlorisocyanuric acid. Swimming pool tablets dissolve more slowly than calcium hypochlorite and do not throughly disinfect the effluent. Additionally, there is a danger of explosion using swimming pool tablets since the tablets will release an explosive gas called nitrogen chloride due to the fact that they are not totally immersed in water at all times while in use. They are not approved by EPA for wastewater effluent disinfection.
Adding Chlorine to Septic System
Chlorine tablets are added via an access port on the top of your aerobic septic system tanks. Usually there are two access ports, one for the chlorine, and one for accessing the aereation chamber. Depending on the system manufacturer’s model, the ports will either be secured by screw-on caps or latched caps. Chlorine tablets usually go in the port that is closest to the spray heads (furthermost from the residence). On most models you will see a tube entering the chlorine port chamber as well as some wires.