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For water to be healthy for us to drink, cook with and bathe in, it needs to meet certain standards. The Australian Drinking Water Guidelines (ADWG) define 'good quality drinking water' and recommend quantity limits of particular substances for human health and safety, and aesthetic quality. Rous County Council aims to ensure that our water supply meets these standards by managing and monitoring the water quality from the catchment to the consumer.
The ADWG describe water quality standards under four main categories:
This includes disease causing microorganisms, or pathogens, as well as cyanobacteria (blue-green algae) and other 'nuisance organisms' that are not harmful to health but may cause problems of taste, odour, colour, scaling or corrosion.
Pathogens include bacteria and viruses, as well as single-celled parasites such as Cryptosporidium and Giardia. These organisms are natural parts of healthy ecosystems and play important roles such as assisting in the decay of organic matter. However human disease can be caused by these organisms, including gastric disorders ranging from mild 24-hour 'bugs' to life-threatening diseases such as cholera. Escherichia coli (E.coli) is used as an indicator for the presence of micro-organisms.
Toxins, bad taste and odour can be produced by blooms of cyanobacteria, which can occur when levels of organic matter are particularly high, usually in warmer weather.
This includes characteristics such as colour, taste and odour, suspended solids, pH, temperature and hardness. The ADWG state that water needs to be 'acceptable to most people'. This means that it needs to be 'clean and sparkling' and people generally find drinking water unacceptable well before the values of contaminating substances indicate a health threat. This can mean more expensive and energy-intensive treatment in order to get water to an aesthetically desirable quality.
Inorganic chemicals can come from a variety of sources such as natural leaching of iron and manganese, dissolved salts from land use activities, small amounts of carryover from treatment chemicals, addition of chemicals such as chlorine and fluoride, and corrosion of pipes and fittings. Iron levels are particularly high in the source water in all Rous County Council catchment areas because of the volcanic nature of the geology (ie, 'red' basalt soils). Manganese levels are also high. Neither element is a threat to health but they make the water look dirty and can stain bathroom and laundry fittings.
Organic compounds and pesticides can be present from natural processes, human activities, or as a by-product of the disinfection process. Water coming from catchments where agricultural chemicals such as herbicides and pesticides are used may contain traces of organic chemicals. Road run-off can result in hydrocarbons entering the water supply.
Drinking water exposure to radiation can come from naturally occurring radionuclides, or from human activities such as mining or manufactured radionuclides made for medical and industrial uses. Screening for radiological concentration has not indicated any activity in Rous County Council sources.