In the era of the Sustainable Development Goals, for which one of the aims is to provide universal access to safe water, sanitation and hygiene (WASH) services, it is crucial to target and prioritize those who remain unserved. Multi-criteria decision analysis (MCDA) models can play an important role in WASH planning by supporting priority-setting and policy-making. However, in order to avoid misleading assumptions and policy decisions, data uncertainty — intrinsic to the available collection methods — must be integrated into the decision analysis process. In this paper, we present two approaches to incorporating data uncertainty into MCDA models (MAUT and ELECTRE-III). We use WASH planning in rural Kenya as a case study to illustrate and compare the two approaches. The comparison focuses on the way these two models handle uncertainty in the available data. The analysis shows that, while both methods incorporate data uncertainty in a considerably different manner, they lead to similar prioritization settings.