Key Takeaways
- Freshwater makes up only 2.5 % of Earth’s water, and climate change, population growth, and rising demand are intensifying water scarcity worldwide.
- Desalination has evolved from a niche solution for arid states to a global industry worth $24–28 billion in 2025, projected to reach $65 billion by the early 2030s, with over 20,000 plants operating in 150+ countries.
- Seawater supplies about 59 % of desalinated output; brackish groundwater (BGW) contributes roughly 22 % and offers higher recovery rates (70‑90 %) with lower energy use than seawater reverse osmosis.
- Reverse osmosis (RO) dominates seawater desalination (2.5‑4 kWh/m³), while electrodialysis (ED) is preferred for BGW; both technologies remain energy‑intensive, with electricity accounting for 40‑50 % of operating costs.
- Currently, <1 % of global desalination capacity is powered by non‑carbon sources; most plants rely on natural gas, oil, or coal, making the sector “carbon‑locked” despite growth in renewables.
- Small modular reactors (SMRs) are emerging as a promising, stable, low‑carbon power source for desalination, offering continuous output, long lifespans, and potential co‑generation of process heat for thermal steps.
- Desalination produces a concentrated brine stream (≈2× seawater salinity); improper discharge harms marine ecosystems, but diffuser technology mitigates impacts, and brine holds promise as a source of critical minerals such as lithium, magnesium, boron, and rare metals.
- Scaling desalination to meet future water deficits will require coupling supply‑side innovations (efficient membranes, hybrid RO/ED systems, nuclear or renewable power) with demand‑side measures like conservation, improved allocation, and better water‑management policies.
The Growing Water Crisis
Water covers more than 70 % of the planet, yet only 2.5 % is fresh, and most of that is locked in glaciers or deep aquifers. Climate change, urbanization, agricultural expansion, and industrialization have intensified demand while reducing freshwater availability. Human water consumption has risen at least 25 % in the last two decades, and extreme heatwaves—such as the June 2026 event in Europe—have pushed regional supplies past critical thresholds, prompting emergency restrictions. The core issue is not water volume but access to safe drinking water, a fundamental determinant of global health. A 2025 World Bank report warns of “mega‑drying regions” where declining reserves meet rising demand, urging action on demand management, allocation, and supply augmentation.
Desalination as a Global Industry
To boost supply, many nations have turned to desalination—the removal of salts and minerals from non‑potable water. Once limited to desert states, desalination now constitutes a booming global industry valued at $24–28 billion in 2025, growing at a compound annual rate of 9‑12 % and projected to reach $65 billion by the early 2030s. More than 20,000 plants operate in at least 150 countries, transforming the technology from an alternative option into a pillar of water security. The Middle East and Africa dominate the market, accounting for over half of global capacity; the Gulf states alone have thousands of plants, with Saudi Arabia aiming to lift its daily desalination output from 5.6 million m³ in 2022 to 8.5 million m³ by 2025.
Feedwater Options: Seawater vs. Brackish Groundwater
Seawater remains the primary feedstock, supplying roughly 59 % of desalinated water worldwide. In contrast, brackish groundwater (BGW)—water with 1,000‑20,000 ppm total dissolved solids—accounts for about 22 % of output. BGW is less saline than seawater (≈35,000 ppm) and yields higher recovery rates (70‑90 %) because lower salt concentrations require less energy. The United States exemplifies BGW use, with over 300 plants, mainly in the West, Midwest, and Florida, tapping vast subsurface resources estimated at 800 times the annual fresh groundwater pumped nationwide. Despite this potential, current BGW desalination captures only a fraction of the available resource, a gap between‑1,000‑2,000 ft deep aquifers.
Energy‑Intensive Technologies: RO and ED
Desalination is inherently power‑hungry. For seawater, reverse osmosis (RO) is the dominant method, using high‑pressure pumps to force saline water through semi‑permeable membranes that reject salts. RO consumes 2.5‑4 kWh per cubic meter of product water, far less than the 5‑15 kWh/m³ required by older thermal distillation processes. For brackish water, electrodialysis (ED) prevails; an electric field drives ion‑selective membranes to extract salt ions, leaving water molecules intact. ED achieves higher recovery rates at low salinities but becomes cost‑prohibitive as salinity rises. Across both technologies, electricity represents 40‑50 % of operating costs, spurring research into membrane efficiency, AI‑optimized operation, hybrid RO/ED systems, and alternative power supplies.
The Carbon Challenge
Despite efficiency gains, the desalination sector remains heavily reliant on fossil fuels. Less than 1 % of global capacity uses non‑carbon energy; in the Middle East, about 93 % runs on natural gas and 6 % on oil, while parts of Asia still depend on coal. This “carbon‑locked” status persists even as renewable energy expands, because RO and ED demand continuous, stable power—something solar and wind alone cannot guarantee without costly storage or backup. Consequently, natural gas is often viewed as the most reliable fossil fuel option if decarbonization is delayed.
Nuclear Power and Small Modular Reactors
Nuclear energy offers a continuous, long‑lived power source that could decarbonize desalination. Conventional nuclear plants already demonstrate the concept: India’s early‑2000s demonstrations, programs in Russia, South Korea, and China, and the US Navy’s aircraft carriers, which use onboard reactors to produce ~1,500 m³/day of fresh water. The advent of small modular reactors (SMRs)—factory‑built, scalable units generating 50‑300 MW—creates a compelling match for desalination facilities. SMRs can provide steady electricity, supply process heat for thermal steps, and operate for up to 80 years, far exceeding the lifespans of solar/wind farms or battery storage. Although no commercial SMR‑desalination plant exists yet, national planning is advancing, and the industry anticipates that nuclear will play a decisive role in achieving a low‑carbon water future.
Environmental Concerns: Brine Waste and Valorization
Every desalination plant yields two streams: product water and brine, a waste stream with roughly twice the salinity of seawater. In 2025, global brine production exceeded 140 million m³ per day—equivalent to more than 50 billion m³ annually, about the volume of Lake Erie. Untreated brine discharge can harm marine life, reducing fish populations and damaging coral reefs. Mitigation technologies such as multiport diffusers disperse and rapidly dilute brine, minimizing ecological impact when properly sited and managed. Beyond waste management, brine is increasingly seen as a resource: its elevated dissolved‑solid concentration enables extraction of critical minerals like lithium, magnesium, boron, potassium, and rarer elements (gallium, scandium, vanadium, indium). Pilot projects have demonstrated brine mining for magnesium, suggesting a pathway to turn part of the waste stream into valuable commodities, though large‑scale “waste‑to‑wealth” conversion remains aspirational.
Toward a Sustainable Water Economy
The world’s water shortfall is not speculative; it follows from arithmetic: a growing population, hotter temperatures, deeper droughts, and depleted aquifers. By 2050, the global population may reach 9.7 billion, intensifying pressure on already scarce freshwater. Desalination is one of the few technologies capable of delivering clean water at the scale required, independent of rainfall or river flow. Yet today, desalination supplies less than 1 % of humanity’s total annual water use, while over 70 % of that use goes to agriculture. To meet mid‑century needs, the sector must both expand output—potentially doubling its share—and adopt demand‑side strategies such as improved allocation, conservation measures, and smarter water‑management policies.
Realizing a sustainable water future will require a combination of advances: higher‑efficiency membranes, hybrid RO/ED systems, AI‑driven plant optimization, and decisive steps toward low‑carbon power—whether through scaling renewables with sufficient storage, embracing nuclear or SMRs, or integrating waste heat from industrial processes. Simultaneously, addressing brine through responsible discharge, diffusion technology, and mineral recovery can mitigate environmental impacts and create economic co‑benefits. As the World Bank stresses, no single technology is a panacea; coupling supply innovations with demand‑side stewardship is essential. By doing so, the global community can harness the Earth’s abundant saline waters to secure clean, safe drinking water for billions, turning a looming crisis into a manageable, sustainable challenge.