The report concerns design aspects for the recently proposed solar barometric distillation technology for seawater desalting (SW-SBD) via underground barometric layout. SW-SBD desalting plants applying one-effect and two-effect distillation technologies are specifically analysed. A salt seawater solution at sub-atmospheric pressure is made to flow in vacuum solar collectors of simple design and construction to absorb solar radiation and to deliver the water vapour which drives distillation processes at operative temperatures below 100 degrees C. The proposed SW-SBD desalting plants have good energy efficiency and promising technico-economic features. Field research on SW-SBD prototype plants is necessary to bring SW-SBD desalting technology to its full technological development.