Desalination's Global Rise: A Critical Solution Amid Water Scarcity
As climate change intensifies droughts, disrupts rainfall patterns, and fuels wildfires, more regions are increasingly turning to the sea for drinking water. Desalination, the process of removing salt from seawater, offers a vital method to produce freshwater in areas lacking sufficient rain, rivers, or groundwater to meet demand. Today, it supplies water to hundreds of millions of people worldwide, from the Middle East to the United States, and its use is growing as water scarcity deepens globally.
How Desalination Works: Modern Methods and Technologies
Most modern desalination plants rely on a process known as reverse osmosis. In this method, seawater is forced at high pressure through a semi-permeable membrane that allows water molecules to pass through while blocking most salts and other impurities. The result is freshwater on one side and a highly concentrated salt solution, known as brine, on the other.
Before the water reaches the membrane, the seawater is typically filtered to remove debris and microorganisms that could clog equipment. Afterward, the freshwater is treated again to meet drinking water standards, often including the addition of minerals for health and taste.
An older method, thermal desalination, involves heating seawater until it evaporates, then condensing the vapor back into liquid, leaving the salt behind. While still used in some regions, it is generally more energy intensive compared to reverse osmosis.
Global Usage and Expansion of Desalination
In the Middle East, countries such as Kuwait and Oman source more than 85% of their drinking water from desalination, according to a 2022 report by the French Institute of International Relations think tank. It is also widely used in parts of Africa and Australia, as well as in the United States, particularly in drought-prone coastal areas like California and Texas.
In some Pacific Island nations, where rising seas have contaminated groundwater with salt, desalination is becoming an increasingly important source of freshwater. More than 20,000 desalination plants now operate worldwide, and the industry has been expanding at about 7% annually since 2010, according to the International Desalination and Reuse Association.
Significant Environmental Trade-Offs and Impacts
Desalination comes with significant trade-offs, primarily due to its energy intensity. Plants worldwide produce between 500 and 850 million tons of carbon emissions annually, according to a 2025 study published in the journal Water Research. This is nearing the roughly 880 million tons emitted by the entire global aviation industry, an estimate from the industry group Air Transport Action Group.
The byproduct of desalination, highly concentrated brine, is typically discharged back into the ocean, where it can harm seafloor habitats and coral reefs by increasing salinity and introducing chemicals used during treatment. Meanwhile, intake systems can trap and kill fish larvae, plankton, and other organisms at the base of the marine food web. These losses can ripple outward, reducing populations of fish and larger predators that depend on them.
Efforts to Reduce Environmental Impacts
Some companies are powering plants with renewable energy, while others are developing more efficient membrane technology to reduce energy consumption. Others are experimenting with moving the process into the deep sea, where natural ocean pressure can help drive reverse osmosis, lowering the need for additional energy.
Many experts say water recycling and conservation should come first, noting that wastewater purification typically uses far less energy than seawater desalination and can substantially reduce impacts on marine life. This approach is seen as a more sustainable complement to desalination in addressing global water shortages.
