This European Standard, together with EN 13476-2 and EN 13476-3, specifies the definitions and general requirements for pipes, fittings and the system based on unplasticized poly(vinyl chloride) (PVC-U), polypropylene (PP) and polyethylene (PE) structured-wall piping systems that are to be used for non-pressure underground drainage and sewerage systems. This standard is applicable to: a) structured-wall pipes and fittings, which are to be used buried in the ground outside a building structure only; reflected by the marking of products by “U”; b) structured-wall pipes and fittings, which are to be used buried in ground both outside (application area code “U”) and within a building structure (application area code “D”); reflected in the marking of products by “UD”. In conjunction with EN 13476-2 and EN 13476-3 it is applicable to structured-wall pipes and fittings with or without an integral socket with elastomeric ring seal joints, as well as welded and fused joints. This part specifies general aspects and gives guidance concerning a national selection of requirement levels and classes where part 2 and part 3 of this standard provide options. EN 13476-2 and EN 13476-3 specify material characteristics, dimensions and tolerances, test methods, test parameters and requirements for pipes with smooth internal and external surfaces, Type A, and pipes with smooth internal and profiled external surfaces, Type B.