2007/22 – Yarralin (Northern Territory) – E.coli, Hardness, Turbidity, Barium, Iron

Yarralin (Northern Territory) – E.coli

2015/16: Yarralin E.coli 3 detections. 92% compliance for the year

“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

Yarralin – Northern Territory – Hardness

2007/08: Yarralin Hardness 383mg/L

2008/09: Yarralin Hardness 396mg/L

2009/10: Yarralin Hardness 384mg/L

2010/11: Yarralin Hardness 380mg/L

2013/14: Yarralin Hardness 367mg/L

2015/16: Yarralin Hardness 347mg/L

2016/17: Yarralin Hardness 352mg/L

2021/22: Yarralin Hardness 300mg/L (av.)


“To minimise undesirable build‑up of scale in hot water systems, total hardness (as calcium
carbonate) in drinking water should not exceed 200 mg/L.

Hard water requires more soap than soft water to obtain a lather. It can also cause scale to form on hot water pipes and fittings. Hardness is caused primarily by the presence of calcium and magnesium ions, although other cations such as strontium, iron, manganese and barium can also contribute.”

Yarralin (Northern Territory) – Turbidity

2009/10: Yarralin Turbidity 6.8NTU

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

Yarralin (Northern Territory) – Barium

2008/09: Yarralin Barium 0.7mg/L

2009/10: Yarralin Barium 1.09mg/L

2010/11: Yarralin Barium 0.96mg/L

Based on health considerations, the concentration of barium in drinking water should not
exceed 2 mg/L.
Barium makes up approximately 0.04 per cent of the Earth’s crust, and is the 16th most abundant nongaseous element. Barium in drinking water is primarily from natural sources. Some barium salts such as the chloride and nitrate are soluble in water; others, including the carbonate, fluoride, phosphate and sulfate, are insoluble. Barium is not considered to be an essential nutrient for humans.
Barium compounds have a wide variety of industrial applications. They are used in the plastics, rubber, electronics, steel, optical, and textile industries. They are also used in ceramic glazes and enamels, in glass and paper making, as a lubricant additive, in pharmaceuticals and cosmetics, and as a rodenticide. The concentration of barium in drinking water overseas is usually low, typically less than 0.02 mg/L.
Most foods contain small quantities of barium. The major dietary sources are milk, potatoes and flour. Some cereal products and nuts can contain large amounts. It has been estimated that average dietary intake is approximately 1 mg per day.
In Australian drinking water supplies, typical concentrations of barium range from <0.002 mg/L to 1.1 mg/L.

Yarralin (Northern Territory) Iron

2007/08: Yarralin Iron 0.66mg/L

2009/10: Yarralin Iron 1.79mg/L

2010/11: Yarralin Iron 0.8mg/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