I have a Victorian end of terrace with the obligatory bathroom built in the back extension. Between the kitchen and the bathroom is the small lobby that the back door opens into, and in this area is a manhole cover (it has been covered with the same floor finish and only the outside frame and brass screws are visible). A scary call to building control revealed that it didn't contravene anything when it went in (ages ago) and it doesn't belong to the water board. As far as I can tell it's only my loo that empties into it as I can't hear water any other time, there is also another manhole in the back garden at the end of my house. I want to extend the kitchen slate floor out into this lobby. I have had one person say not to do it in case I need to open it up, another saying it was ok unless I was flushing very odd things down the loo and likely to block it up! Any advice to sway me either way would be appreciated!