Climate change is already having noticeable effects on water utilities in Nzoia River Basin. Extreme weather and climate-related occurrences are becoming more common and intense, as predicted by the Intergovernmental Panel on Climate Change (IPCC), Third Assessment Report. Because most water utilities are unprepared, the repercussions might be severe. The water supply infrastructure is built for resiliency and sustainability of operations during weather events or other circumstances that could potentially interrupt services; but when events that were historically considered to be “100-year” events happen more and more frequently, utilities must prepare for a new normal. These extreme events are occurring or being exceeded more regularly, and as a result, the past may no longer be a reliable predictor of the future. In Nzoia River Basin, the water supply infrastructure currently designed for historical climate conditions is more vulnerable to future weather extremes and climate change. This study assessed the effect of climate change on drinking water utilities in Nzoia River Basin. A cross-sectional survey design was used. Three counties were randomly selected from the basin for study with Busia representing the lower catchment, Kakamega middle catchment and Trans Nzoia upper catchment. The study was carried out from May, 2017 to September, 2017. In-depth expert interviews and brainstorming sessions were used to identify the climate change impacts affecting drinking water utilities experienced in the last ten years in the basin. A carefully selected team of water and climate change experts consisting of decision makers, practitioners, managers, scientists and technology adopters were used to rank the severity of the climate change impacts. Climate change occurring in Nzoia River Basin is expected to have a wide range of consequences for drinking water utilities. By assessing its potential impacts on water utilities, we become better positioned to make improvements today to decrease the future risks. The results of this study provide valuable insights for the national and county governments in preparing to effectively anticipate and respond to the relevant issues that they can expect to face in the coming century.