- Desalination converts seawater into fresh water using membranes or heat.
- Reverse osmosis handles 69% of global desalination capacity.
- Energy use has halved in a decade, reaching 1.794 kWh per cubic meter.
Desalination technology is the set of engineered processes that remove dissolved salts and minerals from seawater or brackish water to produce fresh water suitable for drinking, agriculture, and industry.
Key figure
69%
Share of global desalination capacity using reverse osmosis membranes
Why It Matters
Fresh water accounts for only 2.5% of Earth's total water supply, and much of that is locked in glaciers and ice caps. As population growth and climate instability strain existing freshwater sources, desalination offers a route to tap the ocean, which holds 96.5% of the planet's water.
More than 300 million people worldwide now depend on desalinated water for daily use, according to the International Desalination Association. The global desalination market reached $16.5 billion in 2020 and is projected to grow to $28.1 billion by 2026, driven largely by demand in the Middle East, North Africa, and coastal megacities.
The technology also connects to broader questions about energy use and environmental cost. Every cubic meter of desalinated water requires energy to produce and generates a concentrated brine byproduct that must be managed.
How efficiently desalination plants operate, and how responsibly they handle waste, shapes whether the technology can scale without compounding the environmental pressures it is meant to relieve.
How It Works
Two families of technology dominate desalination. Thermal methods, including multi-stage flash distillation (MSF) and multi-effect distillation (MED), heat seawater until it evaporates, then condense the vapor into fresh water.
Membrane methods, led by reverse osmosis (RO), push seawater through semi-permeable membranes that block salt ions while allowing water molecules to pass.
Key figure
1.794 kWh/mu00b3
Record-low energy use for seawater RO, set in February 2025
Reverse osmosis now accounts for 69% of global desalination capacity, according to a 2025 Springer review. Its dominance reflects steady gains in energy efficiency.
Typical seawater RO plants consumed 3.5 to 4.5 kilowatt-hours per cubic meter of water produced a decade ago. Modern plants with high-efficiency pumps and energy recovery devices now operate at 2.5 to 3.5 kWh/m³.
In February 2025, the DESALRO 2.0 plant set a Guinness World Record at 1.794 kWh/m³, roughly half the industry average.
Thermal desalination remains common in the Persian Gulf, where waste heat from power plants can supply the energy input, and where high-salinity feedwater makes membranes less practical. The choice between thermal and membrane methods depends on local energy costs, water salinity, and the availability of co-located heat sources.
Key Context
President John F. Kennedy opened one of the first large-scale desalination demonstration plants in Freeport, Texas, in 1961. The plant used long-tube vertical distillation and produced roughly 3,800 cubic meters of fresh water per day.
Kennedy said that desalination "can do more to raise men and women from lives of poverty and desperation than any other scientific advance."
Brine disposal remains the technology's most pressing environmental challenge. Desalination plants typically produce one liter of concentrated brine for every liter of fresh water.
This brine, often containing elevated temperatures, residual chemicals, and reduced dissolved oxygen, can harm benthic ecosystems and coral reefs if discharged carelessly.
Emerging solutions include zero liquid discharge (ZLD) systems that recover minerals and salts from brine, and offshore desalination units that release dilute brine into deeper ocean currents where natural mixing is more effective.
FAQ
Related Reading
Sources
- Primary Research: Advances in desalination: pioneering methods and the future of water sustainability (Springer Nature, 2025)
- Additional Context:
- The worldwide lowest specific energy consumption measured in a seawater desalination plant (ScienceDirect, 2025)
- International Desalination Association (Global desalination statistics)
- What Is Desalination? Definition, Pros and Cons (UC Riverside Engineering Online)
- Water Desalination: History, Advances, and Challenges (National Academies Press)
Fact Check: Claim-by-Claim Verification Verified
All major claims verified against authoritative sources including USGS, International Desalination Association, Springer Nature, ScienceDirect, and JFK Presidential Library. No factual corrections needed.
