This work examines the influence of integrating a sponge layer of several densities on the performance of a
solar still desalination unit (SSDU). Two identical SSDUs are constructed and tested simultaneously; one of
them is used as a reference while a sponge layer is floated in the basin of the second unit. The results report that
applying the sponge to the SSDU changes its operational principles and consequently changes the temperatures
profiles inside the still and its corresponding performance. The maximum freshwater production and the thermal
efficiency are recorded with using a floating sponge of density of 16 kg/m3, with corresponding percentage
increase of +58.1% and +55.4%, respectively, when compared with the reference unit. While the freshwater
productivity and the SSDUs thermal efficiency are reduced with increasing the sponge density between 16 to 35
kg/m3