Waste Backflow

[daddywez]

Anyone help.
Just had shower installed and new sink using old waste system.
The shower does not run away very well (no blockage) and water runs back in shower waste from sink waste.
Unfortunately floor has been tiled and so don't realy want major upheaval.
Any suggestions.

Daddywez

 

[Bahco]

Check for blockage or waste pipe running uphill. You may need to dismantle to do it properly so do it right first time as it will not go away.

 

[Axel]

Might not be enough fall from shower tray / trap to waste outlet.

If so, consider removing tray and refitting it a few cm higher.