treatedwaterareseparatedbythemembrane;thetreatedwaterosmosestotheuntreatedwater.Thereisosmoticpressurebetweenthetwo.Ifthepressureisaddedtotheuntreatedwaterandthepressureoftheuntreatedwaterisbiggerthantheosmoticpressure,thewateroftheuntreatedwaterosmosestotheoppositepositionofthewater.Thisappliesthereverseosmosistothedesaltedwater.ThatistosaytheuntreatedwaterispurifiedintothepurewaterthroughtheROmembraneunderadequatepressure.Theleftwaterwhichcannotosmosisthroughthemembranecontainsalotofsoluteands