Even though water is a renewable resource, most of the water present on the earth's surface is not suitable for direct human consumption. Besides, due to increasing population, urbanization, environmental pollution and growth of industries, the requirement for pure water is found increasing day by day. Also, natural resources of water can meet freshwater demand to only to a limited extent. Hence, there is a need to find a way to purify saline water with the help of an effective water desalination technique. Solar still is one such method which makes use of naturally available sunlight to purify impure/saline water. In this paper, a double-effect passive solar still is designed for experimental investigations to determine the freshwater collected at the output channel. Also, a two-phase, three-dimensional model of the unit is developed in ANSYS FLUENT for the transient state to simulate various temperatures inside the solar still and to estimate the production rate of distilled water produced. The simulation was run for 8 h, and the results have been compared with the experiment performed. Experimental investigations show a total distilled output of 3.2 L/m2 collected in channel, whereas according to analysis results, 3.74 L/m2 output is observed. Here, simulation results follow the similar trend as the experimental results and show good agreement with each other.