Small, rural drinking water treatment (DWT) plants typically use only chlorine to implement the disinfection process. For these plants, free chlorine residual (FCR) serves as a key performance measure for disinfection. The FCR is stated as the concentration of free chlorine remaining in the water, after the chlorine has oxidized the target contaminants.Small, rural drinking water treatment (DWT) plants typically use only chlorine to implement the disinfection process. For these plants, free chlorine residual (FCR) serves as a key performance measure for disinfection. The FCR is stated as the concentration of free chlorine remaining in the water, after the chlorine has oxidized the target contaminants.Engineering[#item_full_content]