Treatment MeasuresRain Water Tanks : Overview
More Information
Comprehensive guidelines for the design of infiltration measures can be found in Chapter 12 "Rainwater Tanks" in the WSUD Engineering Procedures available for purchase from CSIRO publishing.
Many people view water as an unlimited resource and are unaware of the real cost of wasteful water consumption habits. As Melbourne Water encourages water conservation we are supportive of initiatives to reduce water demand by substitution with alternative water resources.
Rainwater tanks are a traditional source of domestic water supply for isolated properties and small communities. In the urban area, rainwater tanks may help save water for some households with appropriate considerations of key factors, to ensure the desired results are achieved.
How Much Water Do You Use?
Water use varies from one household to another. The table below shows how water is used in the 'average' household:
Source: WaterSmart, Melbourne Water, 2001
A rainwater tank can be used to collect rainfall over the winter/spring period for outdoor use, such as garden watering over the summer/autumn period and car washing. If rainwater tanks are used for watering the garden there is the potential to reduce consumption of water from the reticulated (mains) supply by up to 20 per cent. However, based on the average household use of 86kl per year for garden use, a tank to meet all garden needs would be quite large. Most rainwater tanks are smaller than the 'required' tank, meaning that they are generally used as a supplementary supply.
Rainwater Tanks And Their Impact On The Stormwater System
Urbanisation has increased the amount of stormwater runoff into the drainage system due to an increase in impervious areas of land. Rainwater tanks can assist in reducing the amount of stormwater runoff by providing short term detention in the tank during peak storm events (delaying runoff to drainage system). High peak discharges to the stormwater system from a subcatchment could be reduced if all dwellings in the subcatchment had a rainwater tank. The rainwater tank can not always be expected to assist in reducing stormwater runoff as rainfall events will occur at times when the tank is full.
To improve quality of your collected stormwater a filter device should be placed between the roof source and the tank. This device will assist in reducing the transfer of leaf litter, bird droppings and other roof contaminants into your tank and can assist in reducing the maintenance/cleanout frequency.
Benefits Of Installing Rainwater Tanks In An Urban Area
Through installing a rainwater tank you can help make a difference. The opportunity exists for you to install a tank on your property so that you can help minimise your impact on our water resource. It is unlikely your tank will fill regularly throughout the year, so it is more to supplement rather than replace your water needs. The real benefit of installing a rainwater tank comes from your contribution to the more effective use of our finite water supply - every drop counts.