2007/20 – Harrismith (Western Australia) – Iron, pH, Turbidity

Harrismith-  Western Australia – Iron

2007/08: Harrismith (Western Australia)  – Iron 0.3mg/L (Highest level only)

2017/18: Harrismith (Western Australia) Iron 0.32mg/L (max), 0.2mg/L (mean)

2018/19: Harrismith Iron 0.3mg/L (max), 0.21mg/L (mean)

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

Harrismith (Western Australia) – pH (alkaline)

Average pH: 2007 July-2008 June: 8.56 pH units

2011/12 Harrismith TWS (Western Australia) pH 8.52 (av)

2013/14 Harrismith TWS (Western Australia) pH 8.72 (av)

2014/15 Harrismith (Western Australia) pH 8.7 (av)

2015/16 Harrismith (Western Australia) pH 8.76 (av)

2016/17 Harrismith (Western Australia) pH 8.65 (av)

2017/18 Harrismith (Western Australia) pH 8.61 (av)

2018/19: Harrismith (Western Australia) pH 8.56 (mean)

2019/20: Harrismith (Western Australia) pH 9.18 (mean)

Based on the need to reduce corrosion and encrustation in pipes and fittings, the pH of
drinking water should be between 6.5 and 8.5.

New concrete tanks and cement-mortar lined pipes can significantly increase pH and
a value up to 9.2 may be tolerated, provided monitoring indicates no deterioration in
microbiological quality.

pH is a measure of the hydrogen ion concentration of water. It is measured on a logarithmic scale from 0 to 14. A pH of 7 is neutral, greater than 7 is alkaline, and less than 7 is acidic.

One of the major objectives in controlling pH is to minimise corrosion and encrustation in pipes and fittings. Corrosion can be reduced by the formation of a protective layer of calcium carbonate on the inside of the pipe or fitting, and the formation of this layer is affected by pH, temperature, the availability of calcium (hardness) and carbon dioxide. If the water is too alkaline (above pH 8.5), the rapid deposition and build-up of calcium carbonate that can result may eventually block the pipe.

Harrismith (Western Australia) – Turbidity

2007/8: Harrismith (Western Australia) – Turbidity 9.8 NTU (Maximum detection during year)

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