The present invention is directed to a water desalination system that can be used in a home or commercial entity which uses a reverse osmosis or nanofilter membrane element in a unique flow configuration which promotes self cleaning of a membrane element to prevent a buildup of salts and minerals on the membrane surface. The systems use the dynamics of water usage in a water service line, not connected to the membrane to flush a recirculation/reservoir tank that feeds the reverse osmosis or nanofilter membrane periodically. The systems also produce little or no waste effluent that must be dumped into a waste system, thereby wasting water and causing an environmental problem.