Include polypropylene pipes and fittings systems for achievement of draining networks inside buildings. In addition, other special accessories for interior sewage are provided, as well as fastening systems for the interior sewage pipes. The system is used to transport rainwater and sewage inside buildings and it is composed of pipes made of polypropylene with jack and gasket, and a complete range of PP fittings ranging in size between 32 and 160 mm.