Abstract: The present disclosure relates to a method for reducing accumulation of foulants on reverse osmosis membranes and a groundwater desalination system. An example method comprises passing a feedstream of groundwater through a water treatment unit having a plurality of reverse osmosis membranes disposed therein at a first feed pressure, the first feed pressure being greater than an osmotic pressure of the ground water feedstream, thereby producing a flow of a permeate stream and a concentrate stream; reducing the first feed pressure to a second feed pressure being less than the osmotic pressure of the groundwater, thereby generating a forward osmosis backflow of the permeate stream through said membranes into the groundwater feedstream; filtering the resulting mixture of backflow and groundwater; and discharging the filtered mixture with the concentrate stream.