Rainwater Harvesting Renaissance
Rainwater harvesting in the home is the ultimate form of decentralised rainwater storage. Mankind has always harvested rainwater for survival when there has been no other permanent source of fresh water available.
Rainwater Harvesting in Urban Cities
In Australia, harvesting rainwater has been an integral part of life since colonisation. For those that live outside cities today and do not have access to mains water supply, rainwater harvesting is still the only means of collecting fresh water. While in Metropolitan areas, many people will remember being forced to remove their rainwater tanks from their backyards when mains water supply was first connected and that until recently, it was illegal to put a rainwater tank into their backyard.
Climate Change & Drought
Recently, due to climate change, the drought in Australia and changing rainfall patterns, dam levels have been in steady decline over the last decade. The majority of cities in Australia are now experiencing water shortages and have implemented water restrictions. As a consequence, local and state governments now encourage all homeowners to install rainwater tanks to harvest the rainwater from their roofs.
In fact, in many states, new home builders or those commencing home alterations have to install a rainwater tank to meet water saving targets established by the regulatory authorities. For those not building or renovating, there are cash rebate incentives that will be paid based on storage capacity and in some cases, the reticulation of rainwater back into the home.
As a consequence, the rainwater harvesting industry has experienced significant growth in retrofit installations of rainwater storage to homes. Many homeowners are using the captured rainwater for outside applications such watering the garden or topping up their pool in order to minimise the impact of water restrictions. Regulatory authorities now realise that water shortages require different incentives to save water and are starting to offer rebate incentives for connection of rainwater storage into homes so that rainwater is used instead of mains water for non-potable uses such as flushing toilets and laundry.
Storing Water
The burgeoning interest in Australian rainwater storage has resulted in the development of a number of new and innovative products to meet customer requirements of more attractive or less obtrusive tanks. As Australia's population continues to grow, houses are becoming larger and land size is reducing. The end result is a larger amount of rainwater harvesting surface area (being the roofs of houses), but limited land space to be able to store that captured rainwater. The minimum recommended amount of rainwater required for home use is 5,000 litres, but 10,000 litres is preferable due to the continuing changes we are seeing in our rainfall patterns. One thousand litres of rainwater measures one cubic metre and weighs one tonne. So, 10,000 litres measures 10 cubic metres and weights 10 tonnes!
The rainwater harvesting industry has responded by developing new products such as slim line tanks, underground storage tanks and rainwater storage bladders made of materials from polyethylene to metal to PVC. The objective is either to minimise the footprint of a tank on a property, or to utilise previously wasted space. Rainwater tanks come in all shapes and sizes in an attempt to ensure that all possible configurations can be achieved. One of the main difficulties with large rigid tanks (such as plastic, metal and concrete) is that transport and logistics become a major issue and cost (both delivery to the home and access to the home owners preferred location for the tank). The industry has responded by either decentralising manufacturing (smaller factories in more locations) or by developing products that can be easily and cost effectively shipped Australia wide (such as rainwater storage bladders).
Quality of Stored Water
With rainwater being reticulated back into the home, water quality has become more important. Given the nature of our roofs and the environment we live in (large cities with local fauna and large amounts of traffic) it is necessary to filter that water on the way into the rainwater tank or bladder and in some cases on the way into the house from the rainwater tank. Again, the rainwater harvesting industry has developed a range of products to meet these needs.
And if the stored rainwater is exhausted and is no longer available to use inside the home, a new range of products in the form of mains water controllers has been developed to enables the mains water to be turned on automatically when required.
Conclusion
Today rainwater harvesting has become an integral part of our lives and will continue to be so for the foreseeable future. While major infrastructure options such as dams and desalination will be a part of future water supply, with decentralised rainwater storage at our homes we can all contribute to making the community water last longer while learning more about our environment and making a difference.
