The invention discloses a 
chlorine supplementing method for guaranteeing the 
water quality biological stability of a long-distance 
water delivery pipe network, and relates to a 
chlorine supplementing method for guaranteeing the 
water quality biological stability of the long-distance 
water delivery pipe network. The invention aims to solve the problems of low 
residual chlorine concentration and high heterotrophic 
colony number in water at the 
tail of the existing urban and rural overall planning long-distance 
water delivery pipe network. The method comprises the following steps of: mounting a 
residual chlorine on-line 
detector and an on-
line flow meter on a water conveying pipe network; and calculating 
residual chlorine values of other points of the water delivery pipe network through a residual 
chlorine attenuation model, determining an area with the lowest residual chlorine concentration 
limit value, and determining the quantity and positions of chlorine supplementing points according to the 
ammonia nitrogen concentration of filtered water and the residual chlorine attenuation model to supplement chlorine. By adopting the chlorine supplementing method, the problems of low concentration of residual chlorine and high heterotrophic 
colony number in the water at the 
tail of the existing urban and rural overall planning long-distance water delivery pipe network are solved, the biological stability of the 
water quality at the 
tail of the pipe network is effectively guaranteed, and the occurrence of serious peculiar smell in water due to overhigh chlorine input is avoided. The invention belongs to the field of 
water treatment.