The KAWEX trenchless technology is an inverse sleeve fitting technique for rehabilitation of underground water pipes of DN 200 to 1,000. The technology is used for repairs of leaking underground water pipes, where drinking water leaks out of the pipe into the surrounding area. Before the repair, a hydro-mechanical cleaning, a washout and an examination using a camera is performed. The technical procedure is similar to the KAWO technique used for rehabilitation of sewage headers. Differences lie mainly in the basic components used for lining. Materials used for the KAWEX technology are attested for contact with drinking water and are resistant to excess inner pressure. The lining can be fitted using an inverse device or a pressure vessel and cured by hot water or steam. The result is a long-term prevention of drinking water leakage and extending the lifetime of the piping by dozens of years.