sink drainage

[stuartmcc]

I have a bathroom sink which doesnt drain properly. It seems to drain for a few seconds then stops. The water then remains and drains over quite a long period. I have tried to check for blockages. and looked under the floorboard at the plastic drain pipe. I notice that about 3 feet from the sink the plastic pipe is joined to a lead pipe and that has a small u shape loop in it with a screw drain hole at the base. I thought this might be causing an air lock. Is there any purpose to this loop and could I just remove it.

[plumbbob]

The "U" shaped trap should not be there and will be responsible for all sorts of problems. It is possibly where your pipe is blocked - it wouldn't surprise me!