In this work, an attempt has been made to study the effect of water depth on the internal heat and mass transfer in a single basin single slope plastic solar still. The experimental still was fabricated from Plexiglas. The bottom and all sides of the still are made from a sheet of black Plexiglas (3 mm thick). The cover is made from a transparent Plexiglas of the same thickness. The solar still was sealed to reduce the leakage of vapor to the surroundings. The study covers the influence of different environmental and operational parameters on the still productivity. Environmental parameters include solar intensity, ambient temperature and wind speed. Operational parameters include feed water quantity and basin water depth. The operational parameter such as depth of water in the basin is varied from 2 cm to 12 cm to find out its influence on internal heat and mass transfer and hence the productivity of the still. The maximum distillate output of 2.1 L/m(2)/day was obtained with water depth in still basin 2 cm. The maximum efficiency of the experimental still varies from 10% to 34%. The results indicated that with increase in depth of basin water, still productivity decreases.