The working of the plug tap is easiest to analyse. As shown in the figure the fluid passes throu a hole, in the rotatable plug. The rotating plug controls the flow of water . Rotation of 90°, from the closed position , aligns the passage to the tube axis , and hence the water flows.

Here some degree of control of water flow is innate in the construction of this tap. But it suffers from the disadvantage of leakage of water throu the clearance between the plug & the main body.