Desalination pushes water through a selective barrier

In seawater reverse osmosis, pumps apply enough pressure to push water through membranes that reject most dissolved salts. Energy-recovery devices capture part of the pressure left in the concentrated stream, helping modern plants use far less electricity than older thermal methods. Pretreatment protects the membranes; later steps make the product water suitable for a network.

The result is drought-resistant supply, not consequence-free water. Intake systems, electricity sources, coastal habitat and concentrated brine require careful design, while high capital cost can deepen unequal access. In one future, desalination is a limited part of conservation, reuse and watershed care. In a worse one, it postpones demand reform. The same membrane can sit inside either policy.