Abstract: This present invention relates to a method of recovering very efficiently the energy of a waste stream, which is a by product of the desalination process. More specifically, this present invention relates to a method of using the waste stream to pressurize the clean feed. It also uses the invention as a high pressure seawater pump using another fresh water pump as the pressure source. This invention uses as its core technology a removable pressurization element that enables the quick insertion and removal of the pressurization element via a peristaltic process.