26 Feb 2018 – Buddina (Queensland) – E.coli
Incident Description: There was an E. coli detection from a routine sample taken on 26/02/2018 at Pacific Blvd, Buddina from sample tap CL17DS. The result was 1mpn/100ml.
Corrective & Preventative Actions: Localised flushing was undertaken to draw chlorine residuals through the affected area. Further actions to increase chlorine residuals in the network included chlorine tablet dosing at the Pt Cartwright Reservoir, and an increase in water supply from the NPI through the Wurtulla PRV.
A review of the chlorine levels in the area showed that the affected sample tap experienced variable levels of chlorine leading up to the event. A change in source water in the Caloundra scheme contributed to issues with maintaining a satisfactory level of disinfectant to the extremities of the network. An upgrade of the chlorine dosing facility is now planned for this area of the network.
Follow up sample results: Follow up sample was taken 28/2/2018 and returned a result of <1mpn/100ml E. coli.
“Coliforms are Gram-negative, non-spore-forming, rod-shaped bacteria that are capable of aerobic and facultative anaerobic growth in the presence of bile salts or other surface active agents with similar growth-inhibiting properties. They are found in large numbers in the faeces of humans and other warm-blooded animals, but many species also occur in the environment.
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 2011