2013/14 + 2017 Feb – Pomonal (Victoria) – E.coli, Lead

Center map
Pomonal: E.coli 2orgs/100mL
In response to the E. coli detection at Pomonal, Rupanyup, and Sea Lake, further investigations were carried out including several re-samples in the reticulation, double checking the distribution infrastructure and re-checking disinfectant residuals. The E. coli results at Rupanyup and Sea Lake were thought to be due to sampling error.
The E. coli results at Pomonal were due to low chlorine residuals in the balance tank. The tank was drained and flushed to draw in freshwater, and the chlorine residuals
have been maintained at higher levels.

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

Pomonal – Victoria – Lead

Feb 20 2017: Pomonal (Victoria) – Lead 0.017mg/L
Lead incident–Pomonal (Mis-sample). A compliance sample came back from the laboratory, with a lead exceedance at Pomonal, having a concentration of 0.011mg/L as sampled on the 20
February 2017. In response, an investigation was conducted, the location was flushed, and sampling was conducted in multiple locations in the reticulation. During the incident, DHHS was notified. The investigation identified the root cause of the non-compliance was a ‘mis-sample’ due to having a new sampler who was unfamiliar with the sampling site, and taking water from a tap that led to a rainwater tank that fed water to the garden. Following the event: A
review of all drinking water sampling locations was conducted. Ensure all new samplers received sufficient training to perform task. Based on health considerations, the concentration of lead in drinking water should not exceed 0.01 mg/L.


“… Lead can be present in drinking water as a result of dissolution from natural sources, or from household plumbing systems containing lead. These may include lead in pipes, or in solder used to seal joints. The amount of lead dissolved will depend on a number of factors including pH, water hardness and the standing time of the water.

Lead is the most common of the heavy metals and is mined widely throughout the world. It is used in the production of lead acid batteries, solder, alloys, cable sheathing, paint pigments, rust inhibitors, ammunition, glazes and plastic stabilisers. The organo-lead compounds tetramethyl and tetraethyl lead are used extensively as anti-knock and lubricating compounds in gasoline…

Lead can be absorbed by the body through inhalation, ingestion or placental transfer. In adults,
approximately 10% of ingested lead is absorbed but in children this figure can be 4 to 5 times higher. After absorption, the lead is distributed in soft tissue such as the kidney, liver, and bone marrow where it has a biological half-life in adults of less than 40 days, and in skeletal bone where it can persist for 20 to 30 years.

In humans, lead is a cumulative poison that can severely affect the central nervous system. Infants, fetuses and pregnant women are most susceptible. Placental transfer of lead occurs in humans as early as the 12th week of gestation and continues throughout development.

Many epidemiological studies have been carried out on the effects of lead exposure on the intellectual development of children. Although there are some conflicting results, on balance the studies demonstrate that exposure to lead can adversely affect intelligence.

These results are supported by experiments using young primates, where exposure to lead causes significant behavioural and learning difficulties of the same type as those observed in children.

Other adverse effects associated with exposure to high amounts of lead include kidney damage, interference with the production of red blood cells, and interference with the metabolism of calcium needed for bone formation…” ADWG 2011