Rainwater tanks save Melbourne households 137 litres of water per day

Tuesday 15 December 2015

rainwater tank in front of house

In summary

  • New research into the cost effectiveness of fitting rainwater tanks has found an average saving of 137 litres of water per day per household.
  • Depending on tank size, the payback period is between 12.5 to 16.8 years.

With another El Nino climate pattern upon us, Melbourne is facing greater pressure on water supply and homeowners have been encouraged to install rainwater tanks to help make the most of every drop.

New research into the cost effectiveness of fitting rainwater tanks conducted by a team of final year students from Swinburne University of Technology has found an average saving of 137 litres (22.7 per cent) of water per day per household.

The research project earned the team the Australian Water Association’s Victorian Undergraduate Water award.

The students compared water consumption data supplied by Yarra Valley Water from 6390 households in greater Melbourne, that had installed rainwater tanks and received government rebates between 2005 and 2008, with the quarterly billing data of 5116 households that had not installed rainwater tanks.

They found the payback period was between 12.5 to 16.8 years depending on tank size, with the larger tank size having the shorter payback period.

“Our analysis revealed that installing a rainwater tank reduced water consumption by an average of 137 litres per day per household and tank size and garden area have the biggest influence on savings,” group spokesperson Josh Rock says.

“It showed that a 5000 litre tank used for garden watering and in the laundry and/or toilet has the shortest payback period.

“We were some of the first people to use tank volume, garden area and roof area and compare these figures to actual water savings. The data we were provided from Yarra Valley Water contained the tank size of each household and we measured roof and garden areas using Google Earth.”

The students – Josh Rock, Anil Thayalan and Andrew De Silva – completed the research as part of their Bachelor of Civil Engineering (Honours)/Bachelor of Business (Management) final year project.

They are now eligible for the National Undergraduate Water Award which will be announced at the Australian Water Association’s national water conference, Ozwater ‘16, in May 2016.

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