Wastewater sludge was passed through a laboratory solar still in order to determine the dewatering process. A number of parameters describing the distillate and the sludge were measured at the end of each day in order to determine the process behavior under conditions of relatively high solar radiation and temperature levels. It was realized that dewatering is accelerated and further analysis is needed in order to determine optimum conditions and design parameters for a demonstration plant that will operate towards reducing the sludge volume.