ISO 11295:2017 defines and describes families of techniques for the renovation and trenchless replacement (on or off the line of an existing pipeline) of non-pressure and pressure pipelines through the use of plastics pipes, including plastics composites formed in situ into pipes, fittings and ancillary components. It does not include new construction provided as network extension. For each technique family, it identifies areas of application including, but not limited to, underground drainage and sewerage, and underground water and gas supply networks.ISO 11295:2017 provides information on the principles of, but not the detailed methodologies for, the design of plastics piping systems used for renovation or trenchless replacement of existing pipelines, covering:- existing pipeline and site conditions;- functions of the new pipeline;- structural performance;- hydraulic performance;- installation aspects and site impact;- other factors affecting renovation or trenchless replacement technique selection.Necessary work on the existing pipeline prior to renovation and/or trenchless replacement is outside the scope of ISO 11295:2017.ISO 11295:2017 provides information needed to determine viable options and for identification of the optimal technique with regard to a given set of rehabilitation objectives.NOTE It is the responsibility of the designer to choose and design the renovation or trenchless replacement system.It does not specify the calculation methods to determine, for each viable technique, the required amount of lining or replacement pipe material needed to secure the desired performance of the rehabilitated pipeline.