Background: This study focuses on identifying non-technical aspects that influence the sustainability of communal wastewater treatment plants (WWTPs) in a peri-urban area of Indonesia. Methods: A questionnaire survey was conducted by random sampling using a method of descriptive analysis that combines qualitative and quantitative approaches. Economic support for communal WWTPs was measured by the community’s Willingness to Pay (WTP) and Ability to Pay (ATP). Results: The results indicate that social dimension, such as a community’s level of participation are critically important in sustaining communal WWTPs. In addition, institutional dimension influences the degree of satisfaction a community has toward the WWTP management. This support is reinforced by social capital in the form of a philosophy of mutual cooperation, like gotong royong (cooperation by members of a community to achieve a common goal) and swadaya (self-reliance). Conclusions: The findings of this study can be used in Indonesia to make policy recommendations for managing and ensuring sustainability of communal WWTPs on a non-technical dimension. Additionally, gotong royong deserves to be promoted internationally as a fundamental value for fostering participation and contribution.