Well maintained rainwater tanks can provide a good source of water to households. Installing a water tank can decrease household demand on treated supplies of water and reduce stormwater run-off. In urban areas, the public water supply remains the most reliable source of water and should always be used for drinking. However, rainwater can be used for purposes such as flushing toilets, clothes washing, watering the garden or washing cars.
In some areas of the Yass Valley LGA rainwater is the primary source of household water. Generally rainwater is safe to drink, as long as the rainwater tank is properly maintained and the rainwater is clear with little taste or smell. Rainwater can become contaminated with harmful micro-organisms and parasites, with common sources of contamination being bird or animal droppings, roof or plumbing materials and the accumulation of organic material in gutters. It is important to maintain rainwater tanks and associated plumbing to prevent contamination and to ensure the provision of good quality water.
Maintaining safe drinking water in rainwater tanks
Preventing the contamination of drinking water
With current conditions, it is important to ensure your tank water remains clean when the much needed rain finally falls.
Dust, leaf litter, bird droppings and the presence of contaminates in smoke, ash and debris from fires can contaminate rainwater. It is important to minimise the amount of these from entering rainwater tanks.
First flush diverters prevent the first portion of rainwater run-off from the roof from entering the tank. This reduces the amount of contamination from sources such as dust, leaf litter and bird droppings.
If you do not have a flush diverter installed, you can simply disconnect the tank inlet to prevent the first run-off from entering the tank.
If you would like to find out more information about how to maintain your rainwater tanks, please refer to the Guidance on Use of Rainwater Tanks document at the bottom of this page, which is produced by NSW Health.
Disinfection of rainwater tanks
The most common methods to disinfect a rainwater tank is by chlorination, ultraviolet light irradiation or boiling water. Bringing water to a rolling boil disinfects water, most kettles with automatic shut-offs are suitable for this purpose.
Chlorination is effective against harmful bacteria and viruses, and can reduce odours from rainwater. Disinfection can be achieved by adding 40 ml of liquid sodium hypochlorite (12.5% available chlorine) or 7 g of granular calcium hypochlorite (75% available chlorine) per 1000 L to the tank. Enough chlorine needs to be added to ensure at least 0.5 mg/L of free chlorine residual after 30 minutes of contact time.
The Guidance on Use of Rainwater Tanks document at the bottom of this page explains how this can be completed and also provides methods for calculating the volume of water in a tank.
Topping up tanks with carted water
If you are topping up your tank with water from a water carter, ensure that you are being supplied with clean drinking water (potable water). All water carters should comply with the NSW Health Guidelines for Water Carters.
If you require any further assistance or have any inquiries, please call Council and ask to speak with one of our Environmental Health Officers.