Economic viability and resident preferences for greywater reuse in Chile

Water scarcity is one of the main challenges society faces. Hence, alternative water sources, such as greywater, rainwater, or treated wastewater, are becoming relevant. The main objective of the present investigation was to assess the preferences for greywater reuse under two drinking water availability scenarios and its impact on the economic feasibility of greywater reuse at different housing types: (i) houses in a condominium (n = 84), (ii) apartments in 2 to 7-story buildings (n = 98), and (iii) apartments in 8- to 25-story buildings (n = 120). A choice experiment was conducted in the Metropolitan Region of Santiago, Chile. The willingness to pay (WTP) for greywater reuse ranged between 45.97 and 182.65 USD/month/household for people in the 8 to 25 story buildings without water rationing and in condominium houses with water rationing, respectively. The economic feasibility assessment of greywater reuse was based on implementation costs and benefits from water savings and from the WTP estimation. When the economic assessment is based only on costs and benefits with market value, greywater reuse is not economically feasible in none of the six situations modeled. By contrast, only for condominium houses without water rationing greywater reuse is not economically feasible when people's WTP is added to the benefits. These results are useful to support decision-making to promote greywater reuse in areas with water scarcity.