2009 April + 2012/13 – Balnarring (Victoria) – E.coli, Iron

Balnarring – Victoria – E.coli

The eighth E.coli detection was from a routine sample taken at Balnarring Tank, in the Balnarring locality, on 22 April 2009 (one E.coli organism per 100mL) with a free chlorine residual of 0.2 mg/L. The tank is supplied by the Somers-Flinders Pipeline via Tyabb

Reservoir. Secondary disinfection occurs at Tyabb Reservoir to maintain a chlorine residual of 1.4 mg/L of water leaving the Reservoir. The tank was immediately isolated, inspected and dosed to a free chlorine residual of 0.5mg/L. Samples taken at three nearby taps within the reticulation system, taken on the following day, were clear of E.coli. The tank remained off-line during the winter months due to low turnover, and will be put back into the system in summer when demands on the system increase and works to increase turnover are complete. The count was possibly due to windblown contamination entering the tank through partially open eave ventilation. The tank has since been fully sealed.

Escherichia coli should not be detected in any 100 mL sample of drinking water. If detected
in drinking water, immediate action should be taken including investigation of potential
sources of faecal contamination.

“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

Balnarring – Victoria – Iron

2012/13: Balnarring (Victoria)  – Iron 330ug/L (Highest level only)

Based on aesthetic considerations (precipitation of iron from solution and taste),
the concentration of iron in drinking water should not exceed 0.3 mg/L.
No health-based guideline value has been set for iron.

Iron has a taste threshold of about 0.3 mg/L in water, and becomes objectionable above 3 mg/L. High iron concentrations give water an undesirable rust-brown appearance and can cause staining of laundry and plumbing fittings, fouling of ion-exchange softeners, and blockages in irrigation systems. Growths of iron bacteria, which concentrate iron, may cause taste and odour problems and lead to pipe restrictions, blockages and corrosion. ADWG 2011