A numerical study has been carried out to investigate the transient thermal performance of a naturally circulated humidifying/dehumidifying solar still. A comparison of forced circulation performance and the influence of different environmental, design, and operational parameters on the still productivity and efficiency were investigated. The naturally circulated still shows very similar results to that of forced circulation. This finding is of significant technical and economic importance. Different attempts have been considered to investigate the effect of partial storage of basin energy and partial recovery of condensation energy. The results show insignificant changes on still performance. An economic assessment of water production cost was also highlighted and showed that solar stills can challenge other technologies for special applications.