This class provides a comprehensive discussion of all aspects of disinfection with chlorine, the regulatory framework for using chlorine products, targeted pathogens, and the generation of harmful disinfection by-products when chlorine reacts with natural organic materials (NOM) in the water. The disinfection action of chlorine in water and wastewater treatment, the hazards of chlorine and the formation of disinfection by-products is described along with the need for safe chemical handling and storage. This class is designed to help participants recognize how and when to use various forms of chlorine chemicals. Operators will benefit from this one-day course designed to review the benefits and drawbacks of switching from gas to liquid systems. Topics will include principles of feeding gas chlorine, pumping hypochlorite and chlorine dioxide solutions using metering pumps, e.g. diaphragm and peristaltic and preventative maintenance recommendations for both chlorine gas and liquid feed systems.