Very severe troubles of scale formation might be expected when the recovery of water from seawater increases. The main constituents of the scale are CaCO3, Mg(OH)(2) and CaSO4, all of which are salts of alkaline earth metals. Therefore, if a key technology will be developed by which the main constituents of the scale, all alkaline earth metal can be removed and/or separated from sea water, the recovery of desalted water from raw sea water by high pressure reverse osmosis (HPRO) can be increased up to 75-80%, the solubility limit of the remaining scale components. Then, it will be possible to make use of all valuable materials existing in sea water by an integral system which combines conventional recovery technologies with a set of the proposed technologies such as HPRO, alkaline earth metal ions removal process, inorganic ion-exchangers for recovery of trace elements and so on.