This paper applies a ‘comprehensive’ strengths, weaknesses, opportunities, and threats (SWOT) analysis to compare the ‘before and after’ scenarios of integrating a safe water supply (SWS) into a sustainable sanitation system (SSS) in the peri-urban Ger areas of Ulaanbaatar. Qualitative field investigations, including interviews and focus group discussions, are conducted with stakeholders and key informants to collect data on the scenarios before the SSS and to develop a conceptual framework after the SSS implementation. The before-implementation scenario has one strength, that is, the interest of communities and NGOs toward the SWS–SSS integration, which facilitates the acceptance and up-scaling of sustainable technologies. The after-implementation scenario shows additional strengths, such as community acceptance and satisfaction with SSS. The identified weaknesses are attributed to the lack of community-based organizations, community participation, and inter-sector coordination. The marketing of SSS, the involvement of banks and micro-credit systems, and the reuse of treated greywater have been identified as opportunities. The before-implementation scenario identifies the use of pit latrines and the lack of political will as the primary threats, whereas the after-implementation scenario identifies technology innovations for the extreme cold as a primary threat. The application of the SWS–SSS integration in other cases must be investigated further.