Scale inhibition method for permeation unit

The invention discloses an infiltration method comprising passing a draw stream (2) and a feed stream (14) through an infiltration unit (6) for a first period of time. The feed stream (14) is an aqueous stream having a lower salinity than the draw stream (2) and comprises at least one fouling agent. The permeation unit (6) comprises a semi-permeable membrane (8) which allows the passage of water but does not allow the passage of salts. The draw stream (2) passes through the draw side (10) of the membrane (8) and the feed stream (14) passes through the feed side (12) of the membrane (8) such that water from the feed stream (14) passes through the membrane (8) to the draw stream (2). During the first time period, the concentration of the fouling agent in the feed liquid stream is higher than saturation in an area (26) on the feed side (12). Then, within a second period of time, the flow rate of the draw stream (2) to the draw side (10) of the membrane (8) is lower than the flow rate of the draw stream (2) provi