Optimal delivery of social norms feedback to reduce household water consumption

Providing households with consumption feedback can effectively reduce water and energy use. However, the efficacy may depend on the medium and frequency of the messages. In this longitudinal study spanning over two years, we report two experiments on household water use read via meter in the United Kingdom: one manipulating the frequency of feedback ( N = 13,047), and one comparing the medium (email vs. paper) of the feedback messages ( N = 18,896). Overall, the feedback interventions reduced water consumption by around 2%. There were no differences in delivering the treatment monthly vs. 3-monthly, and paper messages were effective, but emails were not. Almost all households reduced their consumption, although the effect was variable. These results inform psychological interventions and cost-effective messaging for water districts and perhaps other types of utilities.