The　presence　of　biopolymers　in　surface　waters　and　their　significance　for　potable　water　supply　have　received　little　attention　previously　owing　to　their　low　concentrations.　In　this　paper,　we　present　the　results　of　an　extensive　study　that　has　investigated　the　role　and　benefits　of　biopolymers　during　the　purification　of　surface　water　with　reference　to　their　specific　biological　and　physico-chemical　properties.　Using　samples　collected　from　two　representative　surface　waters　in　China　and　the　United　Kingdom,　macromolecular　biopolymers　were　separated　and　concentrated　for　subsequent　investigation　of　their　role　in　coagulation,　metal　ion　adsorption,　and　membrane　separation.　Our　results　show　that　biopolymers　significantly　improve　the　antifouling　capability　of　membrane　nanofiltration,　in　combination　with　the　enhanced　conventional　coagulation　performance　and　additional　security　against　several　unhealthy　metal　pollutants　(e.g.,　Fe,　Al,　and　Cr).　We　believe　this　is　the　first　study　that　reveals　the　versatile　benefits　and　the　fate　of　natural　biopolymers　in　surface　water　purification　processes.