IJRREST: International Journal of Research Review in Engineering Science and Technology (ISSN 2278- 6643) | Volume-2 Issue-1, March 2013 1 | Page Present Status of Solar Still: A Critical Review *Bhavsinh Zala, **Kuldip Dodia, ***Hitesh N Panchal *M.E. (Thermal Engineering) Scholar, Gandhinangar Institute of Technology, Gandhinagar, Gujarat, India **Asst. Professor, Mech. Engg. Dept., Gandhingar Institute of Technology, Gandhingar, Gujarat, India ***Asst. Professor, Mech. Engg. Dept., Gujarat Power Engineering & Research Institute, Mehsana, Gujarat, India Abstract — People can survive for day, weeks or months without food, but cannot live for more than a week without water. The body use water for digestion, absorption, circulation, transporting nutrients, building tissues, carrying away waste and maintaining body temperature. The average adult consumes about 2.5 to 3 litters of water per day to drink. Solar still is a device, which can produce water more than 2.5 Liter to 3 Liter of water by improvement in it. Hence, this review paper shows researches done by many scientists on solar still to enhance productivity. 1. INTRODUCTION Adequate quality and reliability of drinking water supply is fundamentally needed of all people. Without potable or fresh water, there is no human life. Industries and agricultural need fresh water without which they cannot function or thrive. Water is therefore, the key to man’s prosperity; it is intimately associated with the evolution of civilization from rivers, lakes and ponds in plenty are becoming scarce because of industrialization and population explosion. 2. SOLAR DISTILLATION 2.1. About Distillation The solar distillation method is an easy, small-scale and cost effective technique for providing safe water at homes or in small communities. Distillation is one of many processes that can be used for water purification. This requires an energy input as heat and the solar radiation can be the source of energy. In this process, water is evaporated, thus, separating water vapor from dissolved matter. The vapors get condensed as pure water. A conceptual diagram showing the process of solar still is shown in Figure 1. Most of the conventional water distillation plants discussed earlier are energy-intensive and require scarce electric power or fossil fuel for operation. But solar energy, despite being much lower grade energy, is ideally suited. The technology involved in distillation of saline or brackish water using solar energy is relatively simple and semiskilled/unskilled operators can carry out its operation and maintenance. Fig. 1. Conceptual diagram explaining the process of solar distillation. Thus, for a small scale decentralized production of potable water by using the brackish or saline water of salinity level < 10,000 ppm or mg/l (10 ppm = 10 mg/l = 0.01 g/l). Solar distillation which is capable of removing bacteria also, is best suited.Nature itself provides most of the required fresh water, through a similar hydrological cycle in which a very large-scale process of solar distillation produces fresh water naturally. The essential features of the hydrological cycle can be summarized as the production of vapors above the surface of the liquids, followed by transport of vapors by winds, then cooling of air- vapor mixture, condensation and precipitation. This natural process is copied on a small scale in basin- type solar stills shown in Figure 2. Fig. 2. Basin-type single slope passive solar still.