A high recovery rate means a high process yield. However, in a desalination process, operation at high recovery results in higher average concentrate salinities in the membrane elements, higher osmotic pressures and higher membrane feed pressures compared to operation at low recovery. In addition, supersaturation of the concentrate can result in more scaling and high membrane flux can result in more fouling. On the other hand, low recovery rate operation directly reduces process yield and can result in excess pretreatment and supply-pumping expenses. Permeate recovery rate optimization, therefore, is a critical exercise for RO process design and operation.