Climate change impacts the vulnerability of drinking water sources to contamination and water shortages. This review highlights key risk factors along the impact chain of climate change on water supply security, from precipitation and runoff to surface water quality and availability at drinking water intakes. How climate impacts water quantity (hydrology) and quality (fate, transport and loads of contaminants, via soils, forests, and urban water infrastructure) is examined across the scientific literature. An emphasis is placed on high-latitude regions, where the kinetics and intensity of projected changes are high. The province of Quebec, Canada, is used as a study area that covers diverse land and climate conditions, with extended relevance at a broader scale globally. This review aims at guiding researchers and water managers in considering the climate-related evolution of a range of threats when assessing the vulnerability of drinking water systems. It highlights how climate change increases the seasonal risks of water supply insecurity in a northern region, thereby increasing socioeconomic and public health risks. Accounting for multiple feedback effects is a major cause of uncertainty in assessing future risks in drinking water supplies. Under deep uncertainty, a paradigm change in assessing climate impacts on water supplies is needed.