2016/18 + 2019/20 – Mountain View/Orchid Valley (Queensland) – Iron, Turbidity, Colour

Mountain View/Orchid Valley (Queensland) – Iron

2016/17: Mount View/Orchid Valley (Queensland)  – Iron 0.421mg/L (max)

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

2016/20 – Mount View/Orchid Valley (Queensland) – Turbidity

2016/17: Mount View/Orchid Valley (Queensland) – Turbidity 8.3NTU (max)

2017/18: Mount View/Orchid Valley (Queensland) – Turbidity 11NTU (max), 0.9NTU (av)

2019/20: Mount View/Orchid Valley (Queensland) – Turbidity 5.5NTU (max), 0.53NTU (av). One result of 5.51 NTU exceeding the aesthetic maximum limit of 5 NTU in April 2020

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

2017/18 – Mount View/Orchid Valley (Queensland) – Colour

2017/18: Mountain View/Orchid Valley (Queensland) – Colour. 33 Pt/Co (max)

“At times colour is above the ADWG guideline criteria….Generally the colour of treated water at GISC is below the ADWG value, however, large spikes were observed in January 2013 due to an increase in the concentration of manganese in the source water.”

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…