2007/18 – Albany (Western Australia) – Hardness, Iron, Total Dissolved Solids, Silica

Albany – Western Australia – Hardness

2007/08: Albany (Western Australia) – Hardness 269mg/L (max)

2008/09: Albany (Western Australia) – Hardness 280mg/L (max), 217mg/L (mean)

2009/10: Albany (Western Australia) – Hardness 260mg/L (max)

2010/11 Albany (Western Australia) Hardness 270mg/L (max), 206mg/L (av)

2011/12 Albany (Western Australia) Hardness 280mg/L (max), 196mg/L (av)

2013/14 Albany (Western Australia) Hardness 250mg/L (max), 210mg/L (av)

2014/15 Albany (Western Australia) Hardness 260mg/L (max), 228mg/L (mean)

2015/16 Albany (Western Australia) Hardness 270mg/L (max), 244mg/L (mean)

2016/17 Albany (Western Australia) Hardness 290mg/L (max), 255mg/L (mean)

2017/18 Albany (Western Australia) Hardness 310mg/L (max), 260mg/L (mean)

GUIDELINE

“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

2009/10 Albany (Western Australia) – Iron

2009/10: Albany (Western Australia)  – Iron 0.36mg/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

2011/12 Albany (Western Australia) – Total Dissolved Solids

2011/12: Albany (Western Australia)  – Total Dissolved Solids 632mg/L (max), 525mg/L (av)

2015/16 Albany (Western Australia) Total Dissolved Solids 614mg/L (max), 578mg/L (av)

2016/17 Albany (Western Australia) Total Dissolved Solids 605mg/L (max), 581mg/L (av)

2017/18 Albany (Western Australia) Total Dissolved Solids 651mg/L (max), 586mg/L (av)

“No specific health guideline value is provided for total dissolved solids (TDS), as there are no
health effects directly attributable to TDS. However for good palatability total dissolved solids
in drinking water should not exceed 600 mg/L.

Total dissolved solids (TDS) consist of inorganic salts and small amounts of organic matter that are dissolved in water. Clay particles, colloidal iron and manganese oxides and silica, fine enough to pass through a 0.45 micron filter membrane can also contribute to total dissolved solids.

Albany (Western Australia) – Silica

2017/18 Albany (Western Australia) Silica 81mg/L (max), 67.5mg/L (mean) (listed as Silcon in Water Corporation Water Quality Report 2017-18)

To minimise an undesirable scale build up on surfaces, silica (SiO2) within drinking waters should not exceed 80 mg/L.
GENERAL DESCRIPTION
Silica present in water is usually referred to as amorphous silica (i.e. lacking any crystalline structure). When silica is dissolved within water it forms monosilicic acid:
SiO2 + 2H2O à Si(OH)4
When the concentrations of monosilicic acid increase, polymerisation of the silica occurs, forming polysilicic acids followed by formation of colloidal silica. Monosilicic acid and polysilicic acids are the forms of silica analysed when determining dissolved silica content.
The deposition of silica from solutions can occur via various mechanisms. The deposition of silica that can cause the most problems for the water industry is via silica’s ability to deposit on solid surfaces that have hydroxyl (OH) groups present. Surfaces that commonly have hydroxyl groups present are glass and metallic surfaces. For example, dissolved silica will react with the surfaces of glass and begin to form a white precipitate. The silica forms silicates on the surface, resulting in silica build-up. In cases where customer complaints occur due to scale build-up, water hardness and silica concentrations should be investigated to determine the cause.
Silica can be a problem in water treatment due to its ability to cause fouling of reverse osmosis (RO) membranes (Sheikholeslami and Tan, 1999, Ning 2002, Sahachaiyunta and Sheikholeslami 2002). This occurs when the dissolved silica of the concentrate becomes super-saturated, causing silicates to form in the presence of metals, and these deposit on the membrane surface. The silicate then dehydrates, forming hard layers on the membrane that reduce the effectiveness of the process… 2011 ADWG