Stirling (South Australia) – pH (alkaline)
Average pH: 2016 July-2017 June: 8.738 pH units
2018/19: Stirling (South Australia). Average pH 8.792 pH units
2019/20: Stirling pH (average) 8.85pH units
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
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.
When pH is below 6.5 or above 11, the water may corrode plumbing fittings and pipes. This, however, will depend on other factors such as the material used, the concentration and type of ions in solution, the availability of oxygen, and the water temperature. Under some conditions, particularly in the presence of strong oxidising agents such as chlorine, water with a pH between 6.5 and 7 can be quite corrosive.
Chlorine disinfection efficiency is impaired above pH 8.0, although the optimum pH for monochloramine disinfectant formation is between 8.0 and 8.4. In chloraminated supplies chlorine can react with ammonia to form odorous nitrogen trichloride below pH 7.
Chlorination of water supplies can decrease the pH, while it can be significantly raised by lime leached from new concrete tanks or from pipes lined with asbestos cement or cement mortar. Values of pH above 9.5 can cause a bitter taste in drinking water, and can irritate skin if the water is used for ablutions.
23/10/20: Stirling (South Australia) Ammonia – Free – as NH3 0.5mg/L
Based on aesthetic considerations (corrosion of copper pipes and fittings), the concentration
of ammonia (measured as ammonia) in drinking water should not exceed 0.5 mg/L.
No health-based guideline value is set for ammonia.
“…Most uncontaminated source waters have ammonia concentrations below 0.2 mg/L. High concentrations (greater than 10 mg/L) have been reported where water is contaminated with animal waste. Ammonia is unlikely to be detected in chlorinated supplies as it reacts quickly with free chlorine. Ammonia in water can result in the corrosion of copper pipes and fittings, causing copper stains on sanitary ware. It is also a food source for some microorganisms, and can support nuisance growths of bacteria and algae, often with a resultant increase in the nitrite concentration.” ADWG 2011