Feasibility of Water Efficiency and Reuse Technologies as Demand-Side Strategies for Urban Water Management
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Potable residential water efficiency and reuse technologies have seen increasing adoption in recent years and have been estimated to reduce demands by up to 50%. This report present the results of an engineering economic model to estimate the technically feasible levelized cost of water provided by seven above-code water efficiency and reuse technologies within Texas Water Planning Region K, representing central Texas. Unlike other demand-side studies of residential water use, we model uncertainty and variation in technology adoption cost and performance; include reuse technologies; and differentiate between new construction and retrofits. A water efficiency and reuse supply curve was developed to compare the levelized cost of efficiency and reuse technologies with conventional supply-side water management strategies. Results show that efficiency and reuse in the residential sector can meet 85% of 50-year projected needs (the difference between projected demand and estimated supplies) for the LCRA service area. Lower levelized costs were estimated for immediate retrofits of most technologies, promoting incentives for early technology adoption. However, efficiency and reuse technology performance demonstrates considerable uncertainty and variability. The fraction of demands met by demand-side strategies range from around 60% to 100%. Occupancy drives much of the variability because it significantly affects demand. These results promote designing incentives for adoption of water efficiency and reuse technologies based upon use. Finally, water-efficient showerheads and bathroom faucet aerators perform well over a variety of assumptions, indicating that these technologies should be a priority for municipalities seeking water demand reductions. The methods presented in this report provide a useful tool for water planners and managers who wish to compare demand- and supply-side water management strategies on an even basis, and introduces assessments of uncertainty and variability not previously seen in the relevant literature. This report has been modified for publication and has been published as a manuscript in the Journal of Industrial Ecology (DOI: 10.1111/jiec.12430).