2014-16: Longreach (Queensland) – E.coli, Turbidity

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2014-15: Longreach (Queensland) – E.coli

Incident Description: Detection of E. coli in the reticulation system. Possible contamination of sample. In-house testing from the same sample point on the same day was clear and had free chlorine of 1.41. Water treatment plant operator also took sewerage samples on the same day and likely contaminated a sample bottle prior to reticulation sample being taken. Corrective and

Preventative Actions: Three additional samples were taken one from the same sampling point, one from before and one from after on the same line. All samples came back clear of E. coli. The line was flushed and staff were retrained on sampling.

Longreach Regional Council Drinking Water Quality Management DWQMP – Annual Report
30 June 2014 – 30 June 2015

“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

Longreach (Queensland) – Turbidity

2015/16: Longreach (Queensland) – Turbidity 187 NTU (Maximum detection during year) (11.83NTU av.)

Longreach Regional Council Drinking Water Quality Management Plan 2015/16

Chlorine-resistant pathogen reduction: Where filtration alone is used as the water treatment
process to address identified risks from Cryptosporidium and Giardia, it is essential
that filtration is optimised and consequently the target for the turbidity of water leaving
individual filters should be less than 0.2 NTU, and should not exceed 0.5 NTU at any time
Disinfection: A turbidity of less than 1 NTU is desirable at the time of disinfection with
chlorine unless a higher value can be validated in a specific context.

Aesthetic: Based on aesthetic considerations, the turbidity should not exceed 5 NTU at the
consumer’s tap