2006/07 + 2020/21 – Seville (Victoria) – E.coli, Lead, Zinc

2006/7 – Seville (Victoria) – E.coli
2006/7: Seville (Victoria) – E.coli 120orgs/100mL
On 28 February 2007, an E. coli test result of 2 organisms/100mL was reported in a sample taken at a customer tap in the Seville water sampling locality. Localised cleaning of water mains and spot chlorination of the Lewis Hill Reservoir were undertaken. E. coli was not detected in the subsequent additional samples collected across the locality.
On 23 March 2007, an E. coli test result of 120 organisms/100mL was reported from a sample taken at a customer tap in the Seville Water sampling locality. The immediate response involved cleaning of the mains and further sampling across the entire water sampling locality. An extensive investigation was undertaken and the area was monitored at 11 sampling locations
across the locality three times per week for a period of three months. E. coli was not detected in any of the routine or additional samples collected during this period. A new water main to increase the turnover of water in the area will be constructed in 2007-08.

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

2006/07 Seville (Vic) – Lead

2006/07 – Seville (Vic) – Lead 0.011mg/L (max)

Lead Australian Drinking Water Guideline 0.01mg/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…ADWG 2011

2020/21: Seville (Vic) – Zinc

2020/21: Seville (Vic) – Zinc. 43.98mg/L (max), 0.003mg/L (min), 11.005mg/L (mean)

Based on aesthetic considerations (taste), the concentration of zinc in drinking water should
be less than 3 mg/L. No health-based guideline value is proposed for zinc.

Zinc is widely distributed and occurs in small amounts in almost all rocks, commonly as the sulfide. It is used as a coating to prevent corrosion of iron and steel products, and in the manufacture of brass. Zinc oxide is an important component in the manufacture of paint and rubber products, including tyres.

In surface and ground waters, the concentration of zinc from natural leaching is usually less than 0.01 mg/L. Tap water can contain much higher concentrations as a result of corrosion of zinc-coated pipes and fittings. Zinc concentrations in galvanised iron rainwater tanks are typically 2 mg/L to 4 mg/L but have been reported as high as 11 mg/L.

Taste problems can occur if the zinc concentration in drinking water exceeds 3 mg/L. Water with a zinc concentration above 5 mg/L tends to be opalescent, develops a greasy film when boiled, and has an undesirable dry ‘metallic’ taste. Zinc is present in plant and animal tissues, and food is the major source of zinc intake. Drinking water usually makes a negligible contribution to total intake. 2011 ADWG