Weird Problem With Draining Basin All aspects of plumbing questions and answers, help, tips and information

[mplayer78]

I have a slow draining basin which feeds into the bath and shower waste then under the concrete floor then through another u-bend to outside. The bath and shower drain with no issue however the basin (which is obviously the highest) has always drained slowly. Weirdly, however, when I run water down the bath the basin drains much quicker. I have change the trap to an anti-siphon type but it doesn’t seem to help much. Any help would be much appreciated!!

[thedoctor]

Hi

It sounds like the basin is connected to the bath or shower before the trap. So when the water runs out of the basin it then sits in the pipe, slowly pushing the bath water out of its trap until its all gone. Remember the bath or shower waste will always have water in it so will slow down any water coming through it.

When the bath runs, the basin will empty much quicker because the water from the bath is already helping with pushing the water through the trap.

Hope this helps