The purpose of this book is going to through the main topics address the design and manufacture of multi-stage solar still connected to the evacuated solar collector tubes (ESCT). thermal energy of salt water is derived from the water heated by (ESCT),Three natural substances will be selected to be used at basins stage of the solar desalination to achieve the best productivity and performance of the solar still,Study the effect of (design, operational and climatic) on the performance of solar still,Study of the thermal effect of evaporation and condensation of saline water on distilled water production. Study the factors affecting the productivity of the best case.