How does desalination turn seawater into drinking water?

The answer

Modern desalination primarily uses reverse osmosis, a process where seawater is forced through semi-permeable membranes at high pressure, allowing water molecules to pass through while blocking dissolved salts. This method has become dramatically more energy-efficient since the 1970s, dropping from about 20 kilowatt-hours per cubic meter to roughly 3 today. The world's largest desalination plant, Ras Al Khair in Saudi Arabia, produces over 1 million cubic meters of fresh water daily. However, desalination produces a concentrated brine byproduct that, when discharged back into the ocean, can harm marine ecosystems. Researchers are working on solar-powered and graphene membrane technologies to further reduce costs and environmental impact.