Desalination plants remove salts and minerals from seawater, brackish water, or treated wastewater, typically using thermal or membrane technologies. Seawater is the most important source of desalinated water globally. Proponents of desalination plants argue [Page 131]that they provide a reliable and secure water supply for areas struggling with water shortages and can alleviate pressure from overstressed and environmentally unsustainable water supplies. Opponents of desalination, on the other hand, cite the negative effects on ecological systems that can result from the intake of seawater and the discharge of brine and by-products by plants, as well as the high energy usage, high costs, and equity issues associated with the technology.

Desalination plants commonly employ thermal distillation or re verse osmosis technology to separate salts from water. Distillation is ...