An open architecture desalination system having a field of water desalination using porous micro filtration or ultrafiltration (MF or UF) membranes followed by high pressure reverse osmosis (RO) membranes for salt removal. A novel integrated system with a unique process flow allowing use of multiple UF and MF membrane configurations on same platform is also disclosed. Additionally, the system utilizes a noble process flow to enable high efficiency operation of the MF and UF membranes thus reducing footprint, longer life of the membranes and reduced energy.