In Bengaluru, as in many places worldwide, rapid urban population growth and climate-change induced water scarcity raise the need for ensuring access to safe water sources and for increasing the capacity to treat wastewater. One solution for both challenges is to treat wastewater close to its source of generation with so-called 'on-site wastewater treatment systems' and to directly reuse it. To increase the use of such systems, the local government of Bengaluru has issued a policy mandating their adoption for part of the population. However, many of the subsequently installed systems are not maintained well, indicating a lack of user acceptance. As user acceptance is crucial for a successful implementation of technologies, investigated how different socio-technical configurations of on-site wastewater treatment and reuse are perceived and accepted by (potential) users, and for which configuration acceptance is highest. In a first step, we conducted stakeholder interviews and workshops to better understand the local context, including the technological systems, the policy environment, the business options, and user perceptions. These insights led to the design of an online experiment conducted with residents of Bengaluru (N = 707), in which a set of different configurations was presented to participants. These configurations varied in terms of: the quality of the water treatment, the financial investments and gains, the reuse purposes, the amount of freshwater saved through reuse (environmental benefit), and the increased water security for users (reduced dependence on unreliable water deliveries by tankers). The analyses revealed that better water treatment quality was related to lower perceived disgust and health risk, but not to higher acceptance, potentially due to the higher financial costs. Moreover, participants were generally open also to close-contact reuse, but only if safety was ensured. I will complete the presentation by showcasing challenges and lessons learned of interdisciplinary and intercultural field work.