Hello, This is a strange one and yes we must be missing something. The Bathroom sink fills up without a plug in it. We disconnected the ubend. We can see the floor clearly through the plug hole itself, the ubend is clear and not blocked and the outlet pipe on the wall has been rodded with no indications of a blockage. So why, when all is reconnected does my bathroom sink start to fill the instant I open up a tap without a plug in it? The water starts to accummulate in the sink instantly and does not drain ! Help! We are at our wits end.