The notion that Porto Santo's Desalination Plant was among the world's first three is frequently circulated, but a closer examination suggests a more complex historical reality.
While seawater desalination is an old practice, with distillation facilities dating back to the 19th century, the Porto Santo unit stood out for adopting an innovative technology for its time: reverse osmosis. This method, which forces water through membranes under high pressure to retain salts, differs from predominant thermal processes.
Documentation from ARM – Águas e Resíduos da Madeira indicates the plant was one of the first industrial reverse osmosis seawater desalination units globally and the first in Europe. Upon its operation in 1980, only five comparable industrial units existed worldwide. Some official sources mention it was "one of the first three global plants to adopt reverse osmosis technology," a more precise formulation, though international literature points to earlier or contemporary installations elsewhere.
