2013 – Mountain View (Queensland) – Cryptosporidium

In 2013 the routine testing program confirmed three Cryptosporidium detections in the
southern rural schemes (Fishery Falls, Mountain View and Bramston Beach), Boil Water
Notices were required to be issued for two of these instances.

Cryptosporidium

“In recent years, Cryptosporidium has come to be regarded as one of the most important waterborne human pathogens in developed countries. Over 30 outbreaks associated with drinking water have beenreported in North America and Britain, with the largest infecting an estimated 403,000 people (Mackenzieet al. 1994). Recent research has led to improved methods for testing water for the presence of humaninfectious species, although such tests remain technically demanding and relatively expensive.

Cryptosporidium is an obligate parasite with a complex life cycle that involves intracellular development in the gut wall, with sexual and asexual reproduction. Thick-walled oocysts, shed in faeces are responsible for transmission. Concentrations of oocysts as high as 14,000 per litre in raw sewage and 5,800 per litre in surface water have been reported (Madore et al. 1987). Oocysts are robust and can survive for weeks to months in fresh water under cold conditions (King and Monis 2007).

There are a number of species of Cryptosporidium, with C. hominis and C. parvum identified as the main causes of disease (cryptosporidiosis) in humans. C. hominis appears to be confined to human hosts, while the C. parvum strains that infect humans also occur in cattle and sheep. C. parvum infection sare particularly common in young animals, and it has been reported that infected calves can excrete up to 10 billion oocysts in one day. Waterborne outbreaks of cryptosporidiosis have been attributed to inadequate or faulty treatment and contamination by human or livestock (particularly cattle) waste.

C. hominis and C. parvum can be distinguished from one another and from other Cryptosporidium species  by a number of genotyping methods. Infectivity tests using cell culture techniques have also been developed. Consumption of contaminated drinking water is only one of several mechanisms by which transmission (faecal-oral) can occur. Recreational waters, including swimming pools, are an important source of cryptosporidiosis and direct contact with a human carrier is also a common route of transmission.Transmission of Cryptosporidium can also occur by contact with infected farm animals, and occasionally through contaminated food.” ADWG 2011

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…