A back to wall toilet is where the pan is fitted fully to the wall or against a specially designed cistern unit. The cistern and all plumbing work is hidden in the wall or the unit, which provides a much neater finish to your bathroom. This creates a clean, contemporary look and is also a space saving solution for small bathrooms and en-suites too. At BigBathroomShop, all back to wall toilets are supplied with a soft close seat, so no more accidental bangs and slams.
http://www.sunletsgroup.com/to....ilets/back-to-wall-w