WASH interventions are essential to support human health, prosperity, and dignity, as they provide the base for an adequate standard of living. In many low- and middle- income countries, especially in rural and low-income areas, decentralized wastewater treatment systems (DEWATS) can offer a solution to convey, treat, and dispose of or reuse wastewater closer to the source and through smaller conveyance networks. In Indonesia, and as such in the Brantas basin in East Java, focus area of this study, the government has recognized DEWATS as their best available option for improving sanitation in dense low-income urban settings. Although the percentage of households with access to proper sanitation in the province of East Java has been increasing steadily, service coverage and the quality of sanitation systems still need to be increased to reach the desired coverage by 2024. Similar to other fields of application, within WASH and concerning DEWATS, stakeholder engagement is key to develop and strengthen integrated and sustainable approaches. Nonetheless, it is challenging to formulate targeted interventions in the watershed since they depend on the willing support of various stakeholders who may have different priorities (even within their own institutions), having diverse (and sometimes conflicting) viewpoints. This may result in stakeholders strongly contesting the appropriateness of various solutions. An exploration of stakeholder priorities is therefore needed to facilitate the application of wastewater treatment technologies. Due to its participatory approach and the type of interpretation that the method allows, Q-methodology was selected to explore this situation. Q-methodology is a set of techniques which allow for the study of ‘subjectivity’, combining statistics with the depth provided by qualitative data. It is composed of the data collection technique (called Q-sorting) and a data analysis step via correlation and factor analysis. In this research, the perspectives and priorities of various stakeholders regarding decentralized wastewater treatment solutions are explored to assess the applicability and acceptability of DEWATS in the Brantas river basin. This aims to identify context-based criteria and challenges to the implementation of DEWATS in the Brantas watershed. Although findings from Q-methodology cannot be generalized for a general population, the findings from this study show strong indication that Surabaya government workers tend to prioritize similar criteria, that Malang community members think more similarly than their Surabaya counterparts, and that if a respondent prioritizes the elements describing the 4-F1 perspective (Basic current needs; Long-term sustainability; Socialization and collaboration; High awareness; Economically conscious) then they are likely to be some type of specialist. Additionally, four distinctive perspectives were identified: a focus on long-term sustainability of the system, although with less defined stakeholder responsibilities; a pragmatic, need-based approach; a preference for community-led approaches with user-friendly systems and greater subsidy availability; and a collaborative, but still community-run, approach with a high feeling of ownership. Further research is needed nonetheless to identify how the levels of agreement and disagreement among the different groups for the various statements presented could be integrated into the design and decision-making process for DEWATS in the region.