This part of ISO 4422 specifies the requirements for the determination of the fitness for purpose of a piping system composed of pipes, joints, fittings and auxiliaries made of unplasticized poly(vinyl chloride) (PVC-U), to be used for buried water mains and services and for water supplies above ground, both inside and outside buildings.

The pipes, joints, fittings and auxiliaries covered by this part of ISO 4422 are intended for the conveyance of cold water under pressure at temperatures up to 20 °C, for general purposes and for the supply of drinking water. This part of ISO 4422 is also applicable to water up to and including 45 °C (see figure 1 in ISO 4422-2:1996).

The requirements specified in this part of ISO 4422 are applicable to assembled pipes, fittings, valves and ancillary equipment which can be demonstrated to conform to the respective requirements of ISO 4422 parts 1,2,3 and 4.