The Plumbers, Gasfitters and Drainlayers Act 2006 defines sanitary plumbing as:

• "the work of fixing or unfixing any sanitary fixture or sanitary appliance, or any associated fittings or accessories:
• the work of fixing or unfixing any trap, waste or soil pipe, ventilation pipe, or overflow pipe connected with or intended to be connected with or accessory to any sanitary fixture or sanitary appliance or any drain (whether or not the sanitary fixture, sanitary appliance, or drain is there when the work is done):
• the work of fixing or unfixing any pipe that:
  (i) supplies or is intended to be a means of supplying water to any sanitary fixture or sanitary appliance (whether or not that sanitary fixture or sanitary appliance is there when the work is done); and
  (ii) is within the legal boundary of the premises on which that sanitary fixture or sanitary appliance is or will be installed (whether or not that sanitary fixture or sanitary appliance is there when the work is done):
• generally all plumbing work associated with any sanitary fixture or sanitary appliance."