Water storage tank structure and operating method for the reverse osmosis water purifying system

A water tank unit (A) comprising:

• a tank (1) having a room (11) defined therein, multiple holes (111, 111a, 111b) defined through a top of the tank (1), the tank (1) having an open bottom (12) to which a bottom cover (13) is connected;
• a control valve (2) mounted atop the tank (1) and having multiple water passages, the water passages including a drainage water inlet passage (a), a drainage water outlet passage (b) and a purified water passage (c) and connected with the holes (111, 111a, 111b) in the top of the tank (1) respectively, and
• a soft bladder unit (3) located in the room (11) of the tank (1) and having a bladder (31) with an axial support shaft (32) connected therein, the axial support shaft (32) having a connection path (33) connected to a top thereof, the connection path (33) connected with the purified water passage (c), the control valve (2) controls drainage water to enter into and to flow out from the room (11) of the tank (1), and when the drainage water enters into the room (11), the drainage water squeezes purified water in the soft bladder unit (3) out from the tank (1).