Post treatment for desalinated and soft water for balanced water composition supply

An H2S04-based calcite dissolution post-treatment process and apparatii for desalinated water are provided. The process comprises separating cations from seawater by ion exchange resin (s) (12) onto which the ions are loaded, contacting the ion exchange resin (s) (12) loaded with the cations with an effluent (1) of a calcite dissolution reactor (10) wherein the cations are exchanged with Ca2+ from this effluent. The Ca2+ concentration of the resulting desalinated water (6) decreases while the cations concentration increases to comply with required quality criteria. Batch type and continuous apparatii by which the process can be carried out are described.