PURPOSE: A water tube is provided to easily open and close the holding space of the water tube while maintaining a waterproof property and to modify the holding space as needed for use. CONSTITUTION: A water tube comprises: a tube body; a storage unit(20); a cover unit(30); and a holder unit(40). The holder unit comprises an annular receiving unit(42); a groove portion(43); and an annular holding end(46). The holder unit is made of synthetic resin and is fixed on the upper part of the storage unit. The cover unit comprises: an inserting end(32); a protrusion part(33); and an annular closing end(34). The annular closing end of the cover unit is expanded from the upper side to the outer side to be tightly attached to the holding end.
