Widening the scope: the direct and spillover effects of nudging water efficiency in the presence of other behavioral interventions

Policymakers and firms use behavioral interventions to promote sustainable development in various domains. Correctly evaluating the impacts of a nudge on behavior and satisfaction requires looking beyond the targeted domain and assessing its interactions with other similar interventions. Existing evidence on these aspects is limited, leading to potential misestimation of the cost-effectiveness of this type of intervention and poor guidance on how to design them best. Through a large-scale randomized controlled trial implemented with a multi-resource utility company, we test the impact of a social information campaign to nudge water conservation over two years. We find that the water nudge significantly decreases water and electricity usage, but not gas. The effect is driven by customers who do not receive nudges targeting the other resources. Customers receiving the water report are also significantly less likely to deactivate their gas and electricity contracts, regardless of whether they receive other reports. Our results suggest that multiple nudges strain users’ limited attention and ability to enact conservation efforts. Users’ constraints in attending to multiple stimuli pose important challenges for designing policy interventions to foster sustainable practices.