The utility model provides a can have enough to meet need interim fire water tank of assembling type building, includes assembles the rectangle box that forms by compression -moulding unit, is equipped with the automatic water supply valve of being connected with the water inlet in the box, and the automatic water supply valve is the ball -cock assembly, the ball -cock assembly is including floating floater, connecting rod and connection the valve at the connecting rod other end of one end interlude in the floater on the surface of water, compression -moulding unit includes the mainboard of vertical setting, the swash plate that sets up along mainboard edge slope and the straight board that sets up along swash plate edge level, the center of mainboard is equipped with outside bellied pressure -bearing curved surface, and the center of pressure -bearing curved surface is the plane, the plane of pressure -bearing center of surface and the interior parallel and level of following of straight board, the interval is equipped with the connecting hole that the connecting piece passed on the straight board, be equipped with sealing material between the straight board. The utility model provides a can have enough to meet need interim fire water tank of assembling type building solves the technical problem that current fire water tank can not carry out water level control to it is loaded down with trivial details to solve the dismouting construction, and the transportation is inconvenient, easy -rusting destruction and the short problem of life.