Life cycle assessment of a commercial rainwater harvesting system compared with a municipal water supply system

What is it about?

In partnership with the American Rainwater Catchment Systems Association (ARCSA), researchers Ghimire, Johnston and Ingwersen teamed up to assess a commercial rainwater harvesting system and compare it to a municipal water supply system in Washington, D.C. Using ARCSA's design, material and cost data provided through the collaboration, their assessment shows that the commercial rainwater system outperforms the municipal water system in all impact categories except Ozone Depletion. The trade-off analyses explore the pump and pumping energy associated with both systems to better understand how to optimize the performance of these systems.

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Why is it important?

Eleven life cycle impact assessment (LCIA) indicators were assessed, with a functional unit of 1 m3 of rainwater and municipal water supply (MWS) delivery system for toilets and urinals in a four-story commercial building with 1000 employees. The commercial rainwater harvesting system (RWH) also outperformed the MWS in Metal Depletion and Freshwater Withdrawal impact categories, regardless of pump energy intensities. They also explored the scenario where an auxiliary commercial RWH system was combined with 50% MWS which reduced Ozone Depletion by 19% with an increase in all other impacts, although still lower than the benchmark MWS system impacts. The approach is transferable to commercial RWH installations at other locations.

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