1 March 2018: Mahers Road Tank (Ballarat system). E.coli
E. coli – 1 MPN/100mL. 215 connections in the pressure supply zone for the network treated water storage tank.
“Informed DHHS and initiated incident team response. Confirmed residual disinfection in the tank and surrounding reticulation system. Reviewed hydraulics of tank and altered operation mode to prevent discharge into the system. Resampled tank. Conducted an external and internal inspection of tank integrity. Some potential minor ingress points on the tank roof identified as the most likely sources of contamination. Sealing program conducted on tank roof and entry hatch, together with cleaning of debris around the air vent as a precaution. Reviewed tank inspection processes. Spot dosed the tank with disinfectant and verified adequate residual in tank and surrounding reticulation. Resamples post corrective actions clear of contamination.
Investigation report submitted to DHHS.” Central Highlands Water Annual Drinking Water Quality Report 2017/18
Thermotolerant coliforms are a sub-group of coliforms that are able to grow at 44.5 ± 0.2°C. E. coli is the most common thermotolerant coliform present in faeces and is regarded as the most specific indicator of recent faecal contamination because generally it is not capable of growth in the environment. In contrast, some other thermotolerant coliforms (including strains of Klebsiella, Citrobacter and Enterobacter) are able to grow in the environment and their presence is not necessarily related to faecal contamination. While tests for thermotolerant coliforms can be simpler than for E. coli, E. coli is considered a superior indicator for detecting faecal contamination…” ADWG