Using hybrid choice models to capture the impact of attitudes on residential greywater reuse preferences

The reuse of treated greywater in a residential setting could contribute substantially to easing problems with water scarcity. This paper argues that preferences in relation to reusing greywater for different uses within the home vary across households and can be driven at least in part by psychological constructs, such as attitudes and perceptions, which might appear irrational at face value from an economic perspective. To better understand heterogeneity in behaviour in a greywater reuse context, data from a stated choice survey were analysed using a hybrid choice model with latent variables, allowing us to incorporate measurable characteristics of the decision makers as well as other elements that cannot be measured directly (e.g. attitudes towards greywater reuse). Our results provide evidence on the preferences for different uses of treated greywater, and about the heterogeneity of choices among individuals and uses. The model suggests that heterogeneity in the acceptance of greywater reuse can be linked back mainly to underlying attitudes, for all uses except drinking. This knowledge can be used as an input to evaluate diffusion strategies to increase greywater reuse acceptability focused on messages about its direct (i.e. water bill savings) and indirect benefits (environmental benefits, water security, autonomy).