For your info: Following is extract from the Regulations: (With respect I am coming to the conclusion that your regular plumbing contributors wouldnt know the regulations if they fell on them)
1 Plumbing systems to complyPlumbing systems must be designed, installed and maintained to meet the regulations' requirements. Plumbing materials and fittings must be of a suitable standard. It is not illegal to sell unsuitable fittings and appliances but to install one would be illegal, so check suitability before purchase. The regulations list the standards which fittings must meet and the Water Fittings and Materials Directory, published by the Water Regulations Advisory Scheme (WRAS)
If you would care to read it again you will see it is a Govmnt funded scheme to protect the health of the public when it comes to the conveyance of water.