The water infrastructure sector will account for over 50% of global climate adaptation costs. Simultaneously, half the worldwide population doesn't have access to drinking water or live in water-stressed countries. By 2025, two-thirds of the world's population may face water shortages. With the increasing population living in urban areas, cities are urged to find smart, effective, and efficient ways to manage urban water. We will present how water digital twins can be used as holistic, efficient, data-driven solutions to adapt and reduce climate-related water quantity issues (floods, water loss, droughts, emergencies) with better-informed decisions in planning, designing, and operational stages.