• Warning pipe

    An overflow pipe whose outlet is located in a position where the discharge can be readily seen. Interpretation given in Schedule 2: of the Water Supply (Water Fittings) Regulations and Scottish Water Byelaws read more

  • Water Quality Regulators

    Various regulatory bodies are responsible for enforcing the legislative requirements to protect the health of consumers and ensure both public supplies meet the requirements of the EU Drinking Water Directive. Some regulators are empowered to read more

  • Water trap

    Water seal that prevents backflow of odour from the drain Interpretation given in the Regulators’ WC Suite Performance Specification read more

  • Water Undertaker

    The role of a water undertaker is defined in a number of sections of the Water Industry Act 1991. Water Industry Act 1991 read more

  • WC dual flush

    Flushing cistern with two modes of operation, one delivering a larger volume than the other in which: the larger (full) flush is not greater than 6 litres: and the reduced smaller flush option is not greater than two-thirds the volume of the read more

  • WC flush volume

    Volume of water discharged from the flushing device during a flush cycle. [Note: in the case of devices that require a continuous water supply during flushing (e.g. for outlet seal and/or trap refill) the inflow during flushing forms part of the read more

  • WC flushing device

    Device fitted to a cistern to provide a controlled measured volume(s) of water to a WC for flushing. [Note: a flushing device can be a siphon, drop valve, flap valve or pressurised cistern etc. For the purposes of the WC Specification the read more

  • WC inlet valve

    Valve that controls and shuts off the flow of water into a cistern, usually by an arm connected to a float. Interpretation given in the Regulators’ WC Suite Performance Specification read more

  • WC suite

    WC pan combined with either a flushing cistern with an integral warning pipe connection - or a device deemed to be no less effective device – and an inlet/outlet devices, or a pressure flushing valve, with a WC and flushing device installed read more

  • WC warning level

    Level of spillover of a vertically mounted warning pipe connection or the invert of a horizontally mounted warning pipe connection, or the level at which an equally effective (warning) device would operate. Interpretation given in the read more

  • Wholesomeness

    Wholesomeness is defined in section 4 of the Water Supply (Water Quality) Regulations 2010, the prescribed concentrations and values being set out in Schedule 1 of the same legislation. The Water Supply (Water Quality) Regulations 2010 read more


    The WIAPS Coordinating Group reports to the WRAS Board on matters regarding the administration of the scheme. It's purpose is to raise awareness of the Water Supply (Water Fittings) Regulations and (Scotland) Byelaws and promote compliance with read more


    WIAPS is an approved contractor scheme administered by WRAS on behalf of sixteen water undertakers. read more

  • Workmanlike manner

    The installation, connection, alteration, repair or disconnection of a water fitting must be carried out in a workmanlike manner, which is to say the work must be carried out so as to conform:- to an appropriate British Standard, a European read more

  • WRAS

    WRAS Ltd is a subscription membership company limited by guarantee. Its purpose is to contribute to the protection of public health by preventing contamination of public water supplies and encouraging the efficient use of water by promoting and read more

  • WRAS Approval

    WRAS Approval is one of the ways in which compliance with Regulation 4 (2) & (3) of the Water Supply (Water Fittings) Regulations and Scottish Water Byelaws can be demonstrated. WRAS Approval is unique in that it is the only approval granted read more

  • WRAS approval number

    All WRAS approvals are given a unique 7 digit approval number: the first four digits denoting the year and month when an approval was granted. read more