Relationship between bacterial regrowth and some physical and chemical parameters within Sydneyʹs drinking water distribution system

A sampling program was set up within the Water Board (Sydney) drinking water distribution system to determine the presence and extent of bacterial regrowth. System, physical, chemical and microbiological parameters, including the identification of bacteria isolated, were measured over a 14 month period and correlation analysis was carried out. Results showed that regrowth was present within the system and that certain parameters, such as turbidity and distance from the initial treatment point, correlated with the presence of high bacterial numbers. Identification of bacteria isolated on m-Endo broth indicated Klebsiella oxytoca as the principal coliform involved. High numbers of Aeromonas hydrophila were also isolated.