
Ref to question of Mr Awais
P trap is an intelligent device which makes sure that water seal is present all the time, which does not allow smell to come otherwise there is horrible smell all the time on the distal end of Pipe, This p Trap should be in all places no matter WC or Tub or basin water. I think you Plumber installed simple pipe and bend to at least one of water out lets. It can easily be Fixed. Just see the diagram to understand the Function of water seal.