Water regs (Water Supply (water fittings) Regulations 1999) is enforced by the Water Undertaker (usually the local water co) = Reg 10.-(1)
OFWAT make sure the undertakers enforce the water regs.
Both the installer and the user (you) are responsible for, and may be liable for offences committed un der the regs. However, reg 7.2 provides for owner or occupiers of premises to be excused from their responsibility on the following conditions...IF:
the work in question was installed by a contractor approved by the water undertaker (i.e. WRAS qualified) and the contractor cerified that the fitting was in compliance with the regs. Im not sure how that works in real life though.
British Standard 6700:2006 s 5.8.1 covers accessibility of pipes and fittings i.e. in purpose made chases and 18.104.22.168 "There shall be adequate provision of movement of the pipe relative to the floor by the use of a sleeve properly bonded into the floor"
BTW 6700 has been superseded by BS EN 806 but hasnt changed much.
Coincidentally Ive just got in from taking my Cold Water exam (95%, passed with distinction ) this evening which is based on the water regs. Im taking my water regs exam in a few weeks hopefully. Ive just taken all that stuff above from the water regs training pack on my lap for revision for my hot water exam tomorrow night ...