2010 November + 2016/21: Keith (South Australia) – NDMA, Trihalomethanes, Ammonia, pH

Keith (South Australia) – NDMA

The Highest NDMA levels recorded in South Australia 2007-12 were at Keith 140ng/L 17/11/10 and Lower Lakes 130ng/L 24/2/10 and 17/11/10.

Australian Drinking Water Guideline NDMA: 100ng/L (0.1ug/L)

N-Nitrosodimethylamine (NDMA) can be created through water treatment via cholorination or chloramination or organic nitrogen containing waste water. NDMA is highly toxic and a suspected carcinogen. It was widely discovered in groundwater in California in the late 1970’s as a by-product unsymmetrical dimethylhydrazine (UDMH), which is a component of rocket fuel that requires NDMA for its synthesis. Eight other nitrosamines of interest in drinking and
recycled water are: N-nitrosodiethylamine (MDEA) , N-nitrosodi-n-propylamine (NDPA) , N-nitrosodi-n-butylamine (NDBA) , N-nitrosomethylethylamine (NMEA) , N-nitrosomorpholine (Nmor) , N-nitrosopiperidine (Npip), Nnitrosopyrrolidine (NPyr) and N-nitrosodiphenylamine ((NDPha) .

“More recently, rubber components such as valves and joiners/0-rings that are used in treatment plant pumps and in distribution systems have been found to leach significant levels of nitrosamines into the water supply (Morran etal., 2011). .. In Australia, chloramination is widely practiced and in South Australia the South Australian Water Corporation implemented a routine monitoring program for NDMA in four systems in 2007. From these results it is
clear that the levels in the distribution system vary considerably with time, indicating a seasonal influence due to variations in detention time controlled by demand. There was also evidence of a strong influence of water quality during a period of high flow, colour and turbidity in the river feeding the treatment plants. However, the average concentration of NDMA of more than 750 samples analysed from 2007 to present was low, < 20ng/L. Knight et at. (2011) recently reported nitrosamine data from five drinking water treatment plants in South-East Queensland. Three
of these plants practice chloramination, one uses chlorination, and the other a combination of ozone and chlorine fordisinfection. ” Source: NDMA ATTRACTING INTERNATIONAL ATTENTION The latest news on nitrosamines G Newcombe, J Morran, J Culbert

Keith (South Australia) Trihalomethanes

Breaches to Australian Drinking Water Guidelines Levels Only

19/12/2001 Keith Elm St Trihalomethanes – Total 540 ug/L

Trihalomethanes Australian Guideline Level 250μg/L (0.25mg/L)

Why and how are THMs formed?
“When chlorine is added to water with organic material, such as algae, river weeds, and decaying leaves, THMs are formed. Residual chlorine molecules react with this harmless organic material to form a group of chlorinated chemical compounds, THMs. They are tasteless and odourless, but harmful and potentially toxic. The quantity of by-products formed is determined by several factors, such as the amount and type of organic material present in water, temperature, pH, chlorine dosage, contact time available for chlorine, and bromide concentration in the water. The organic matter in water mainly consists of a) humic substance, which is the organic portion of soil that remains after prolonged microbial decomposition formed by the decay of leaves, wood, and other vegetable matter; and b) fulvic acid, which is a water soluble substance of low molecular weight that is derived from humus”. Source: https://water.epa.gov/drink/contaminants/ind

Keith (South Australia) – Ammonia

November 2 2016 – Keith (South Australia) Ammonia Free as N 0.57mg/L

November 2 2016 – Keith (South Australia) Ammonia Free as NH3 0.69mg/L

May 17 2016 – Keith (South Australia) Ammonia Free as N 0.55mg/L

April 19 2017 – Keith (South Australia) Ammonia Free as NH3 0.56mg/L

May 17 2017 – Keith (South Australia) Ammonia Free as NH3 0.67mg/L

2018/19: Keith (South Australia). Ammonia 0.51mg/L (max for 2018/19)

17/3/21: Keith (South Australia) Ammonia – Free – as NH3 0.52mg/L

21/4/21: Keith (South Australia) Ammonia – Free – as NH3 0.57mg/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

Keith (South Australia) – pH (alkaline)

2016/17: Keith (South Australia) Average  9.023 pH units

2018/19: Keith (South Australia). Average 9.125 pH units

2019/20: Keith (South Australia) average 9.23pH 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
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.

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.