Factors affecting coliform bacteria growth in distribution systems

Abstract

Laboratory studies were carried out to determine which factors influence the survival and growth of coliforms, particularly Klebsiella pneumoniae, in drinking water distribution systems. Tubercle material scraped from the lumen of distribution pipes adversely affected the maintenance of a free available chlorine residual and supported K. pneumoniae growth. The pH of the water markedly influenced the survival of bacteria; 50 percent of the organisms survived at least 22 hours at pH 7.3 and 7.9, whereas 50 percent of the organisms survived only 1 hour at pH 9.0. The addition of lime to the raw water was an effective method of pH and bacteria control. The addition of more than 5 mg/L lime to the raw water caused at least 99 percent reduction in K. pneumoniae levels. The lime addition method was successfully employed to control the growth of this bacterium in the distribution system at Halifax, Nova Scotia, Canada.