This paper presents a theoretical and experimental work performed on a double slope single basin and double basin solar still. In this work, an additional basin is incorporated with conventional single basin still to improve the performance of the double slope solar still. Single basin and double basin double slope stills are fabricated with the same area and tested under the same climatic condition. This study investigates the effect of varying the water mass in both upper and lower basin on productivity of the double basin still. In addition, the results were compared with the single basin still. From this tests (theoretical and experimental), it was found that providing an additional basin increases the productivity significantly. A good agreement was made with theoretical and experimental results. The deviation between theoretical and experimental was within 10%. Double basin still production is higher than the single basin still by 85% for the same basin condition. (C) 2013 Elsevier B.V. All rights reserved.