The Water Industry Approved Plumbers' Scheme (WIAPS) is managed by the Water Regulations Advisory Scheme (WRAS) Ltd on behalf of the majority (20 of 23) of the Water Undertakers in England & Wales; it does not apply to areas that are geographically covered by Severn Trent Water, Anglian Water or Thames Water.
WaterMark is administrated by Severn Trent and in order to become a WaterMark member, a plumber has to show he has been suitably trained as a plumber, that he has adequate knowledge of the Regulations by passing an assessment and that he has sufficient public liability insurance cover.