1. A water treatment process comprising the steps of:conditioning inflowing raw water to reduce scale forming materials therein;pressurizing the conditioned water;subjecting the pressurized water to a first membrane separation process to produce a permeate and a concentrate;treating the concentrate from the first membrane separation process to reduce scale forming materials therein;pressurizing the treated concentrate;subjecting the pressurized concentrate to a second membrane separation process to produce a permeate and a concentrate;subjecting the concentrate from the second membrane separation process to a thermal concentration process to produce condensate and carbon dioxide;mixing the permeate produced in the first and second membrane separation process with the condensate from the thermal concentration process; andinjecting carbon dioxide produced during the thermal concentration process into the said mixture of permeate and condensate to produce a potable water.