In this report, we present a theoretical analysis of a basin type solar still with internal and external reflectors. The external reflector is a flat plate that extends from the back wall of the still, and can presumably be inclined forwards or backwards according to the month. We have theoretically predicted the daily amount of distillate produced by the still throughout the year, which varies according to the inclination angle of both the glass cover and the external reflector, at 30 degrees N latitude. We found the optimum external reflector inclination for each month for a still with a glass cover inclination of 10-50 degrees. The increase in the average daily amount of distillate throughout the year of a still with inclined external reflector with optimum inclination in addition to an internal reflector, compared to a conventional basin type still was predicted to be 29%, 43% or 67% when the glass cover inclination is 10 degrees, 30 degrees or 50 degrees and the length of external reflector is half the still's length. (C) 2010 Elsevier Ltd. All rights reserved.