The recent development of new generation LPRO and LPNF membranes has received attention for application in the field of wastewater and water treatment through an increasingly stringent regulation for drinking water purposes and water reclamation. This paper presents the pilot scale membrane separation studies on Buyukcekmece Lake in Istanbul with low pressure reverse osmosis (LPRO) and low pressure nanofiltration (LPNF) membranes. The application to treatment of anionic and cationic pollutants (Na+, Mg2+, Ca2+, Cl-, So(4)(2-), NO3-) has been investigated as a function of transmembrane pressure and recovery rate under very low pressure range (3, 4, 5, and 6 bars), Flux value increased with increasing pressure and the membrane type of TFC-S gave the highest fluxes. The rejections of ions were increased with transmembrane pressure for two types of membranes. TFC-HR membrane rejection performance was better than the TFC-S membrane for all anionic and cationic pollutants. As recovery rate rises, the rejections were decreased.