Only a fraction of new homes in Victoria are being built with rainwater tanks as standard, compared with nearly all new houses in NSW, according to the Rainwater Harvesting Association of Australia.
Current plumbing regulations in Victoria make it mandatory for new homes to come with either a rainwater tank or a solar hot water system. But the optional nature of the regulations means most most builders choose the solar hot water option as standard, with only a “handful”of builders choosing rainwater tanks, according to Stuart Heldon, director of the RHAA. While some builders are offering tanks as an extra, only around 10 per cent of new homes in the state are installing them, Mr Heldon told The Fifth Estate.
This is causing Victoria to lag behind in water efficiency compared with places such as NSW, where BASIX regulations has led to rainwater tanks in 90 per cent of new homes and measured water savings of 39 per cent compared to the baseline target.
The reason water tanks aren’t being preferenced comes down to money. A cost-benefit analysis performed by ACIL Tasman found that rainwater tank installation had a higher cost to the homebuyer than a solar hot water option. A benefit-cost ratio for solar hot water was 1.2-1.8 over 10 years, and only 0.8-1.2 for water tanks.
As an added blow, those installing solar hot water systems can receive financial assistance through the federal government’s Small Scale Renewable Energy Scheme. In Victoria there are no rebates for rain tanks in new homes, with money only available for homes that received a building permit before 1 May 2011. Installing a rainwater tank after a house had been built was much more expensive than designing it in before construction, Mr Heldon said.
ACIL Tasman, in its report, said the financial case for rainwater tanks would be stronger “if water prices more closely reflect scarcity or if there was greater roof capture and connection to more end uses”.
Mr Heldon said the RHAA agreed that more economically realistic costing of mains water would provide more incentives for alternative water supply, and said the current building code in Victoria was leaving water efficiency behind.
Rainwater tanks had financial benefits outside the individual homes also, he said, and could save the community billions of dollars in water infrastructure and improve water quality in rivers and waterways.
“Reducing mains water consumption reduces the cost of transporting water and operating the water network and reduces the size of water treatment infrastructure,”Mr Heldon said. “Rainwater tanks reduce localised flooding during heavy rain events. When rainwater tanks are included in a new housing development, stormwater infrastructure costs can be reduced, making each housing lot more affordable.”
The Office of Living Victoria, which the government set up to deliver its urban water reform, is currently working on a cost-benefit analysis around improving the water performance of houses, buildings, precincts and communities using the planning provisions and building code.
It also recently released a discussion paper on whole-of-water-cycle management and greater use of rainwater, stormwater and recycled water for non-drinking purposes in each metropolitan subregion.
Executive director for planning and projects Cathy Wilkinson said the Right Water campaign on using alternative water sources was helping to reduce potable water use.