This research proposes a new approach for increasing the productivity of solar still distillation units (SSDUs) while reducing environmental pollution and global warming by exploiting the wasted thermal energies from industrial and domestic applications as an additional heating source for the SSDU. This field study is accomplished by testing two SSDUs simultaneously; the first is a conventional SSDU, and the second is attached with an air duct beneath its base inside which a set of guide vanes is fitted on the lower horizontal side of the duct at several angles (0°–135°). Hot air flows through the duct simulating the waste heat source at several mass fluxes (1.45–6 kg/m2.s). The findings show that the heating airflow raised the temperatures and enhanced freshwater production and system thermal efficiency. The improvements are boosted by increasing the airflow rate and expanding the vane angle up to 120°. After a full day of testing, the modified SSDU achieved maximum productivity of 17.13 L/m2 and thermal efficiency of 34.2 %. Compared to the conventional SSDU, the modified SSDU showed maximum enhancements of 442 % in freshwater productivity and 66.8 % in thermal efficiency, leading to a reduction of the total cost of producing 1 L of freshwater by 70.5 %.