2017/18 – Coonamble (New South Wales) – Hardness, Iron

2017/18 – Coonamble – New South Wales – Hardness

The levels of calcium in Coonamble’s water supply are very close to that suggested in ADWG causing some difficulties to users, particularly with scale on electrical appliances and evaporative air conditioners.


“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.”

 2017/18: Coonamble (New South Wales) Iron

The presence of iron in the town water supplies has been a problem since the introduction of reticulated water over 50 years ago. Dissolved iron leads to rust stained water that not only impacts on the washing of clothes, but also leads to visible stains on sinks, toilets and the exterior of buildings. The removal of iron from reticulated water will rectify these problems…

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