Water management system for a hydrogen engine

A water management system for a hydrogen engine can reduce the volume of a water tank for storing therein cooling water to be injected to the hydrogen engine, and eliminate the need to refill the water tank. The water management system includes a water tank including a main space portion configured to store therein water for cooling the hydrogen engine and a sub space portion into which exhaust gas generated in the hydrogen engine is supplied. The water management system also includes: a water pump, provided in the water tank, to supply water stored in the main space portion of the water tank to the hydrogen engine; and an exhaust line, provided between the hydrogen engine and the water tank, and configured to deliver exhaust gas, containing water vapor, discharged from the hydrogen engine to the sub space portion of the water tank.