A non-potable supply is water that has not been treated, is not monitored and may not meet the Australian Drinking Water Guidelines. Non-potable means 'not for drinking'. Some towns in NSW are declared non-potable. People living in, renting or visiting these towns need to be informed about the risks from the water supply.
A non-potable supply is different to the arrangement in towns with a raw water supply, where a drinking water supply is piped to houses and a second, untreated supply is provided for garden watering and other outside uses. Where a town has a non-potable supply it is the only water piped to properties.
Local water utilities that manage non-potable supplies should assess the risks for these supplies. To carry out a meaningful risk assessment the utility will need information about the source water including information about the catchment, results for inorganic chemicals and radioactivity and any history of cyanobacteria (algal) blooms which will help them to provide the right information to the public.
Advice to 'Boil before drinking' will be appropriate where the main risks are from pathogens. Most non-potable supplies can be made safe by for consumption by boiling.
More detailed advice on boiling water before use can be found on the What to do if a boil water alert is in place webpage. This includes the advice that bottled water or cool boiled water should be used for drinking, washing uncooked food (for example, salad vegetables and fruit), making ice, cleaning teeth, gargling and pet's drinking water, also that tap water is safe for bathing.
Declaring a non-potable supply to be 'Boil before drinking' means that the town has an ongoing boil water alert.
If there are persistent chemical or radiological detections above Australian Drinking Water Guidelines then 'Do not drink' advice would be needed. Boiling will not make the supply safe. Advice of 'Do not use' may be appropriate during a cyanobacteria (algal) bloom with significant toxicity and may be time limited. Local water utilities should contact their local Public Health Unit to discuss 'Do not drink' or 'Do not use' advice.
Local water utilities should use a range of methods to communicate the risks of a non-potable supply with the public. People livingin, renting, or visiting these towns need to be informed about the risks from the water supply. It is important that anyone who may use this water gets the message.
Many non-potable supplies are chlorinated. There is longstanding advice that chlorine should be dosed at a high concentration in non-potable supplies. This helps to provide some disinfection benefit, despite the high chlorine demand, and provides a tastable indicator that the water is not for drinking without first being boiled.
Many properties in regional NSW have their own water sources. NSW Health provides advice about the use of rainwater, surface water (such as farm dams, rivers and creeks) and groundwater. NSW Health recommends that both surface water and groundwater are not used for drinking, cooking and personal hygiene (including cleaning teeth and bathing) without testing and appropriate treatment, including disinfection.