Hi, we have a bath that has been connected through a macerator and won't fully drain. Macerator is a Stuart Turner WC4C. It has been plumbed so that the sink and bath pipes go into a single connector on the macerator. WC on the other side. Bath drains most of the way then we are left with a few inches that can stay for days. We have to flush the loo constantly to trigger the macerator into action to suck out the bath water. When completely gone from the bath the water sits in the trap at a visible level. If we use the sink, the level will come up into the bath again. Need help in finding a fix. Should we plumb the bath directly into the waste water outflow - copper pipe...looks like around 22mm heading out of the macerator? Any suggestions - except remove bath and install shower (bath has to stay) - greatfully recieved. Thanks!