Public-private partnerships (PPPs) are often used for infrastructure development because they can increase investment, increase the efficiency and competitiveness of the infrastructure market, and reduce the government’s monopoly on infrastructure development. Water sector projects have an important role in overcoming the challenges of providing clean and sustainable water for the community. Sustainability is an important factor in the success of water supply projects. This study conducts a systematic review of previous research on the success factors in water supply system projects using the PPP model. This study aims to identify the use of research methods related to critical success factors by analyzing 16 relevant papers. There are quantitative and qualitative approaches to collecting research data. Several studies used different methods based on the analysis of research methods from 16 indexed papers. One of the topics discussed in the water supply system is the discussion of critical success factors in the PPP scheme. Research methods on the topic of critical success factors in water supply systems with PPP systems vary and use different approaches. Previous research has also used several different data collection techniques. The mapping results show that the use of a mix of methods between quantitative methods and qualitative methods as well as literature study techniques is the most dominant. Therefore, the results of this analysis will help further research methods on the topic of critical success factors in water supply systems with PPP schemes.