I've just had a Quadrant steam/shower cabin fitted. When used the shower tray fills with water very quickly and then takes 6 minutes to drain away! The shower tray has it's own little trap and the plumber also fitted a u bend underneath the floor so the fall to soil pipe is steady but not steep. The manufacturer says the tray should not fill with water at all. What can be the cause of the water taking so long to drain away?
Since posting we have the two sinks also slow to drain and also siphoning before joining the same soil pipe which has had the vent removed!