Hi,
I got a new concealed cistern toilet a few weeks ago. All seemed fine but last week the water became discoloured about two hours after flushing. It is not backing up and the flush works fine leaving the water clear but after a few hours a light amber colour develops which becomes a deeper amber as time goes on. If there is a blockage I would expect the level to at least increase but it does not. Any suggestions as to cause and fix?