An in-depth review of over 20,000 Melbourne households revealed significant greenhouse gas (GHG) emissions, energy consumption, and associated costs that may be lowered through greater water efficiency.

Water use in Melbourne houses accounts for 3.8 per cent of GHG emissions, which is comparable to total domestic and international travel in Australia.

Researchers from Monash University and The University of Queensland have indicated that a Melbourne-wide program entailing a simple shower head retrofit could reduce customer bills by $160 and lower GHG emissions by between 98 and 226 kilo-tonnes per year, which equates to taking 21,000 to 49,000 cars off Melbourne roads.

Monash University Sustainable Development Institute Professor and Director of BehaviourWorks Australia Liam Smith said: “We explored which behaviours could result in the greatest water-related energy savings and found that showering behaviours such as installing an efficient shower head and reducing one’s shower time by two minutes were both easy and effective.

“Other behaviours identified that helped mitigate costs included insulating pipes, installing a heat pump water system as well as a water and energy feedback meter in the shower.”

The Net Zero Carbon Water Cycle (NZCWC) Program identifies technical, behavioural and enabling factors that lead to sustainable reductions in water-related energy (electricity and gas) GHG emissions.

Researchers are calling for a holistic reevaluation of the current water cycle and are available to comment on a proposed pathway where the costs and benefits to consumers are considered, rather than just utilities, and for service providers to act on a different set of priorities that deliver genuine “least cost and energy” solutions.

University of Queensland Professor Steven Kenway said: “Australian households aren’t aware that heating water in their homes is the second largest energy demand, equating to around 40 per cent of an average household’s energy use. The energy benefits of water efficiency are often hidden. As consumers, we tend to only think of the savings to our water bills, when in reality our electricity and gas bills are also significantly impacted.

“Regulatory changes are needed to elevate the priority of water efficiency for the multiple benefits it creates.”