2008/17 – Wodonga (Victoria) – Turbidity, Colour, Iron

Wodonga – Victoria – Turbidity

16/10/10–17/10/10 Wodonga LL1 Dirty Water – elevated turbidity in reticulation (~13NTU)

Heavy rainfall within the catchment resulted in significant turbidity levels, which coincided

with changes to process configuration that led to blocked filters and subsequent elevated turbidity in drinking water. Response was rapid, which included significant flushing of water mains, as well as

shutting down of pump stations, which isolated the turbid water to localised sections of the reticulation. Extensive monitoring was undertaken. Longer term actions included implementation

of more rapid automated plant shutdown, stricter protocols when introducing process

changes as well as improved infrastructure flexibility to run non compliant water to waste.

2010/11: Wodonga (low level) Turbidity 15NTU

2011/12: Wodonga (low level) Turbidity 10NTU

2013/14: Wodonga (low level) Turbidity 8NTU

2014/15: Wodonga (low level) Turbidity 18NTU

2016/17  Wodonga (high level) Turbidity 5.8NTU

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.

Wodonga –  Victoria – Iron

2015/16:  Wodonga (low level) Iron 0.61mg/L

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

Wodonga (Low Level) (Victoria) – Colour

2008/9 Wodonga Low Level (Victoria) – Colour 16HU (highest level)

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…