There are many types of traps which are used for fixing water closet (W.C) that is Indian or European W.C at ground floor and upper floor in multi storey buildings. Different types of traps generally used are T-trap, S-trap and Q-trap. All these traps have water seal which prevents entry of bad smell into the toilet/rooms from outer sewer line where the trap is connected to dispose of waste water. Generally T-trap and S-trap are used at ground floor. W.C, Q-trap is used on upper floor in multi storey building. Q-trap has more water seal than P-trap and is more suitable for upper floor. The fixing of Q-traps is useful as it prevents entry of bad smell to the rooms.