This paper studies a system to evaluate the flow rate gains in fresh water production when temperature and salt concentration changes. A pressurised system of single effect, operating at constant pressure of 80 mmHg, has been used to control the operational conditions. The distillation process has been conducted under variable evaporation temperature and salt concentration. The results have shown that there is a dependence of the production of fresh water on temperature and salt concentration whose effects are more significant as the temperature rises and salt concentration lowers. The production of fresh water can be increased by 100%. The use of low concentrated salt and sea water solutions, 20 g/l or lower, increase the production of fresh water by 33%, while at high concentrated solutions, 170 g/l or higher, the use of brine and salt water produce the same amount of distilled water. (C) 2004 Elsevier Ltd. All rights reserved.