2008/12 – Dean (Victoria) – E.coli, Lead, Turbidity, Colour

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Dean (Victoria): E.coli

8/7/08 (3 days) E.coli 5 orgs/100mL: Dean clear water storage tank, Dean. Dean Reticulation. Inspection of tank and resample. No E. coli detected in resample. Informed DHS of initial and resample results. (Central Highlands Water Annual Drinking Water Quality Report 2008-9)

14/2/11 (3 days) E.coli 1 org/100mL: Site investigation and resample collected. Confirmed disinfectant levels at entry point and reticulation, and checked online trends. No E. coli detected in resample. Informed DH of initial and resample results. Decision to relocate sample point to a more representative location. (Central Highlands Water Annual Drinking Water Quality Report 2010-11)

“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

Dean  (Victoria) Lead

2011/12: Dean – Lead 0.01mg/L

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

Dean – Victoria – Turbidity

2008/09: Dean (Victoria) – Turbidity 8.1 NTU (Maximum detection during year)

2010/11: Dean (Victoria) – Turbidity 11 NTU (max), 0.9 NTU (average)

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.

Dean  (Victoria) – Colour

2008/09: Dean (Victoria) – Colour Apparent 30 HU (Highest Level Only)

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…