Abstract In a field experiment among 9,823 customers of the Namibian water utility, we implement interventions to reduce nonpayments. The interventions are based on diagnostic surveys to identify key obstacles to payments. They address informational frictions and apply psychological commitment techniques to narrow the gap between customers’ willingness to pay and actual payments. Initially, payments increase by 29% to 55%, making the interventions highly cost-effective. Removing informational frictions has a lasting impact, but the commitment techniques produce only short-term effects. We demonstrate the effectiveness and limitations of behavioral interventions in settings where heavy-handed tools (e.g., disconnecting nonpayers) are difficult to implement.