A leak-proof water valve includes a water inner tube, an outer tube group and a buoyant housing. When the sealing plug of the toilet tank is leaking, leak-proof structure of a buoyant housing for automatically detection is provided to stop the water inlet valve supplying water, so that a user could be aware of the leaking situation to thereby avoid the waste of water resources.

A leak-proof water valve includes a water inner tube, an outer tube group and a buoyant housing. When the sealing plug of the toilet tank is leaking, leak-proof structure of a buoyant housing for automatically detection is provided to stop the water inlet valve supplying water, so that a user could be aware of the leaking situation to thereby avoid the waste of water resources.