This Technical Specification is applicable, in conjunction with the other parts of ISO 21003 (see Foreword), to multilayer piping systems intended to be used for hot and cold water installations inside buildings for the conveyance of water — whether or not the water is intended for human consumption (domestic systems) or for heating systems — under specified design pressures and temperatures appropriate to the class of application (see Table 1 of ISO 21003-1:2008). It gives guidance for the assessment of conformity, to be included in the manufacturer's quality plan as part of the quality system. It includes: – requirements for materials, components, joints and assemblies given in the applicable part(s) of ISO 21003; – requirements for the manufacturer's quality system (e.g. ISO 9001 [2]); – definitions and procedures to be used if third-party certification is involved. NOTE – If third-party certification is involved, it is recommended that the certification body be accredited to ISO/IEC Guide 65 [3] or ISO/IEC 17021 [4], as applicable.