For the purpose of enhancing concrete performance and conserving freshwater, we proposed a new technique of making desalinated sea sand concrete. Salinity qualified desalinated sea water with alkaline potential is obtained through a set of self-made dual membrane electrodialyzers and membrane electrolyzers. Sea sand is sluiced by the obtained desalinated sea water before it is made into concrete. The desalinating device is portable and easy operating, and outputs qualified sea water to the requirements of desalinating sea sand. The method of sluicing sea sand is proved to be practical and effective. It is found that, comparing to standard concrete, concrete made of desalinated sea sand and alkaline potential water has better mechanics performance and better protection for steel bars. Both desalinated sea water and sea sand contain a certain amount of OH- ions, which helps reducing the ratio of Cl-/OH- in concrete and thus inhibit the Cl- ions from rotting or carbonating concrete; concrete durability is therefore enhanced.