Feasibility of Rainwater & Greywater in Commercial Buildings

Over the last 3 years, rainwater harvesting and greywater recycling systems in 8 commercial buildings were investigated to gain an understanding of their operational performance and the saving opportunities.

From over 300 survey responses, cost was listed as the primary barrier to installation – as well as the biggest incentive. However, education appears to be the main overarching barrier to uptake. Furthermore, one of the largest perceived drivers to uptake was the positive impact on the water network in terms of delayed infrastructure, environmental benefits and resilience.

A key finding in this work is the perceived health risk associated with rainwater and greywater systems. The 8 case study buildings have provided an excellent baseline for both good and poor system design – leading to several learnings that can be adopted in future engineering design guidance. Buildings in Auckland, where volumetric wastewater charges exist, had the greatest financial incentive for reducing water use.