The solar still is potential to augment clean water supply in the rural and low-income settlements. However, the current efficiency of the device is low. In this study, we report the fabrication and experimental performance analysis of a high-efficiency multiple-mode solar still�tagged Desal-1.5. The solar still was investigated in passive mode, relying entirely on natural insolation. Both desalination and ordinary water purification experiments were conducted on the device using seawater and moderately polluted lake water, respectively, between 09:00 and 18:00 h of Malaysia's tropic weather. The optimum freshwater yield of the prototype within the interval was 5780.5 ml/m2, while the optimum solar-to-vapor conversion efficiency, evaluated using the transient latent heat of vaporization, was 161.4. Furthermore, for the first time on a solar still geometry, condensate loss due to condensate collection channel slope has been estimated in this study for our Desal-1.5. The loss amounted to 18.5 of the actual condensate collection. Eventually, water quality assessments of distillates from the device showed good compliance with both WHO and Malaysian drinking water standards. Thus, the recommendation of the solar still to ameliorate freshwater scarcity and support sustainable clean water provision in the rural and low-income regions is strengthened. © 2021 Elsevier Ltd