2007/17 + 2021/22 – Engawala/Alcoota (Northern Territory) – Hardness, Iodine, Turbidity

Engawala/Alcoota (Northern Territory) – Hardness

2007/08: Engawala Hardness 389mg/L

2008/09: Engawala Hardness 405mg/L

2009/10: Engawala Hardness 301mg/L

2010/11: Engawala Hardness 383mg/L

2013/14: Engawala Hardness 359mg/L

2015/16: Engalwala Hardness 372mg/L

2016/17: Engalwala Hardness 356mg/L

2021/22: Engalwala Hardness 400mg/L


“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.”

Australian Drinking Water Guidelines 2011

Engawala/Alcoota (Northern Territory) – Iodine

2007/08: Engawala Iodine 0.22mg/L

2008/09 Engawala Iodine 0.15mg/L

Iodide: Based on health considerations, the concentration of iodide in drinking water should
not exceed 0.5 mg/L.
Iodine: No guideline value has been set for molecular iodine.
The element iodine is present naturally in seawater, nitrate minerals and seaweed, mostly in the form of iodide salts. It may be present in water due to leaching from salt and mineral deposits. Iodide can be oxidised to molecular iodine with strong disinfectants such as chlorine.
Molecular iodine solutions are used as antiseptics and as sanitising agents in hospitals and laboratories.
Iodine is occasionally used for the emergency disinfection of water for field use but is not used for disinfecting larger drinking water supplies. Iodide is used in pharmaceutical and photographic materials. Iodine has a taste threshold in water of about 0.15 mg/L.
Iodide occurs in cows’ milk and seafood. Some countries add iodide to table salt to compensate for iodide-deficient diets.

Engawala/Alcoota (Northern Territory) – Turbidity

2009/10: Engawala Turbidity 13.2NTU

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.