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Nowadays despite of limited water sources, the number of household RO units that fed by brackish water or manmade river, are increasing rapidly. Recent study revealed that the amount of clean water produced by such RO units to that being treated are in best situations below 30%. Therefore, the need to limit or even eliminate the use of small scale RO units is of high priority. This cannot be achieved without providing alternative solutions for clean and pure water supply. Membrane distillation (MD) is one of these solutions for pure water problems. It’s an emerging technology that combines the merits of thermal driven process with membrane separation techniques with almost full water recovery. This study is an attempt to design and develop desalination units of any desired capacity by adapting concepts of MD technology. The targeted MD units for pure water production are of small scale and suited in complete packages comparable to those of RO. To achieve this, a computer program was developed to carry out the required calculations towards designing a MD module with any desired production capacity. In comparison to RO, each MD water production package need to consist of a pretreatment filtration system, pumps, heat exchangers, MD module and water vessels. In addition to piping network and required instruments for fully automatic operation of the unit. For the production of 1000 liters/day of pure water, the surface area of the required membrane distillation module was predicted to be of 0.0107 m2, when feed temperature is set at 50oC and cold side water set at 25oC. The total heat load (including the power consumed by the cooler …