2017/20 – Coen (Queensland) – E.coli, Colour, pH

2017/18 – Coen (Queensland) – E.coli
Coen Water Supply had a non-compliance in July 2018. The sampling site at the depot returned a result of 1 CFU/100ml for E. coli. The non-compliance was reported to the regulator on the 07/07/2018. Water lines in the depot area were flushed and the follow up samplestaken had nil detection for E.coli. The Coen depot is the end of the water line andfeeds the two depot houses. At the time of the non-compliance, one house was empty and the residents of the other were on holiday, therefore there was minimal water use on that line.

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

Coen (Queensland) – Colour

2019/20: Coen (Reticulation) Colour 29HU (max), 8.2HU (av.)

Based on aesthetic considerations, true colour in drinking water should not exceed 15 HU.

“… Colour is generally related to organic content, and while colour derived from natural sources such as humic and fulvic acids is not a health consideration, chlorination of such water can produce a variety of chlorinated organic compounds as by-products (see Section 6.3.2 on disinfection by-products). If the colour is high at the time of disinfection, then the water should be checked for disinfection by-products. It should be noted, however, that low colour at the time of disinfection does not necessarily mean that the concentration of disinfection by-products will be low…

Coen Treatment Plant (Queensland) – pH (alkaline/acidic)

2019/20: Coen (Queensland) 6.97pH (av). [9.93pH (max), 6.07pH (min)]

Based on the need to reduce corrosion and encrustation in pipes and fittings, the pH of
drinking water should be between 6.5 and 8.5.

New concrete tanks and cement-mortar lined pipes can significantly increase pH and
a value up to 9.2 may be tolerated, provided monitoring indicates no deterioration in
microbiological quality.

pH is a measure of the hydrogen ion concentration of water. It is measured on a logarithmic scale from 0 to 14. A pH of 7 is neutral, greater than 7 is alkaline, and less than 7 is acidic.