This paper presents a theoretical study of the thermal performance of a single-sloped basin still with enhanced evaporation and a built-in additional condenser. The still was built so that one of its cover sides (the condenser) is tilted to be parallel to the sun rays and, therefore, be in the shaded area. The condenser heat capacity and surface area (finned) could be increased so that it will always be cooler than the other glass cover sides and act as a more effective heat and mass sink. Enhancing evaporation is carried out by adding black dyes in the still basin to improve basin absorbitivity and increase evaporation surface area. The proposed still design is simple and is not more complex than the conventional design. The effect of different design, operational, and environmental parameters on still performance are studied. The most influencing parameters are found to be solar intensity, base insulation effectiveness, basin mass, evaporation surface area and condenser inner reflectivity. Other parameters such as condenser material, mass, outer emissivity and surface area, cover angle, and wind speed were found to be of less importance. The effect of glass cover frequent instantaneous cooling (up to once every hour) was also investigated as one of the operational parameters and was found to have insignificant effect. Factors having the most influence were combined together and found to produce a yield of about 55% over the base case.