Key takeaways
- The World Health Organization says over 2 billion people live in water-stressed countries, and 2.2 billion did not have safely managed drinking water in 2022.
- Desalination turns salt water into fresh water. The USGS says more than 300 million people get their water from desalination plants, but it is energy-intensive and costs about twice as much as other sources at one major US plant.
- Water recycling, which treats wastewater to high standards, is already in use: the EPA says over 500 US facilities recycle water, and Orange County, California, turns wastewater into drinking water for about a million people.
- The “breakthrough” technologies you read about are mostly not what is supplying water today. Reverse osmosis and wastewater purification are.
This article is general information based on USGS, EPA, WHO and the Orange County Water District. It is not a forecast.
Why it matters
The WHO says that in 2021 over 2 billion people lived in water-stressed countries, a situation it expects to be made worse in some regions by climate change and population growth. In 2022, 73% of the world’s population (6 billion people) used a safely managed drinking-water service, meaning water on their premises, available when needed and free from contamination. The remaining 2.2 billion did not. Those figures are the latest in WHO’s 2023 fact sheet, so newer numbers may exist.
Two big technologies are making new supply: desalination and water recycling.
Desalination: turning salt water into fresh water
The USGS (the US Geological Survey) explains that humans can’t drink saline water, but it can be made into fresh water. Ocean water has about 35,000 parts per million of dissolved salt; fresh water has less than 1,000.
Two methods:
- Distillation: boiling seawater and condensing the steam. The USGS notes it’s one of humanity’s oldest water treatment methods.
- Reverse osmosis: forcing salty water through a semi-permeable membrane that lets water through but not salt. The USGS says it’s effective but more expensive than other methods.
How much is being used?
According to the USGS, citing the International Desalination Association, more than 300 million people globally receive water from desalination plants. It gives these examples:
- The Claude “Bud” Lewis Carlsbad Desalination Plant near San Diego, the largest in North America, produces 50 million gallons a day for 110,000 customers and “costs about twice as much as other water sources.”
- The Jebel Ali plant in Dubai was described as the world’s largest, producing over 588 million gallons a day.
- In the United States, desalinated seawater or treated brackish groundwater is used for public supply in several states, including Florida, California and Texas.
Why isn’t there more of it?
The USGS says the primary reason is cost: “It requires a lot of energy to break the chemical bonds” between salt and water, and the technology is expensive. Environmental concerns matter too. In 2022 the California Coastal Commission declined a proposed plant at Huntington Beach after a 20-year effort, citing higher water rates, marine life loss and impacts on nearby low-income households. The plant would have taken in 100 million gallons of seawater a day, desalted half, and returned the rest as saltier brine.
Water recycling: reusing what we already have
The EPA describes water reuse, also called recycling or reclamation, as treating and repurposing wastewater or stormwater for uses from landscape irrigation to drinking water. It says:
- Over 500 facilities in the United States recycle water.
- It can help in droughts (48 US states had drought in 2024), supply industry, protect rivers from nitrogen pollution, and protect groundwater from saltwater intrusion.
- Treatment removes or destroys germs (through filtration and disinfection with chlorine, ultraviolet light or ozone) and removes chemicals with advanced membranes and filters.
- Examples include San Antonio (golf courses, zoo and industry), Hampton Roads, Virginia (replenishing groundwater), and an East Bay, California utility that supplies about 7.5 million gallons a day to a refinery, which the EPA says conserves enough drinking water for over 83,000 residents.
A big example: Orange County, California
The Orange County Water District’s Groundwater Replenishment System says it is “the world’s largest water purification system for indirect potable reuse.” It takes highly treated wastewater that would have gone to the Pacific Ocean and purifies it in three steps: microfiltration, reverse osmosis, and ultraviolet light with hydrogen peroxide. The district says it:
- produces 130 million gallons a day, serving 1 million people, and meeting 35% of the area’s water demand;
- has operated since January 2008;
- meets all state and federal drinking water standards; and
- uses “one-third the energy required to desalinate seawater.”
(The EPA’s page gives the figure as “up to 100 million gallons per day,” so the exact number depends on the source and year. The energy comparison is the district’s own claim.)
Desalination vs recycling: a quick comparison
| Desalination | Water recycling | |
|---|---|---|
| Source | Seawater or salty groundwater | Treated wastewater or stormwater |
| Key technology | Reverse osmosis or distillation | Filtration, reverse osmosis, UV or ozone |
| Cost and energy | Energy-intensive, expensive (USGS) | Operator reports about one-third the energy of desalination at one major plant |
| Where used | Coastal and arid regions, ships | Cities, industry, farms, groundwater recharge |
What about the breakthroughs?
Headlines often announce new membranes, solar stills or other advances. We did not research individual claims for this article. What the sources show is that today’s working supply comes mainly from reverse osmosis desalination and from advanced purification of recycled water. If you see a “breakthrough,” ask whether it is running at a real plant and what it costs, not just whether it worked in a lab.
What you can do
- Check local water restrictions and your utility’s conservation advice.
- Learn where your water comes from. Many utilities publish this in an annual report.
Frequently asked questions
How many people use desalinated water? The USGS, citing the International Desalination Association, says more than 300 million people.
Is recycled water safe to drink? The Orange County district says its purified water meets all state and federal drinking water standards. Treatment removes germs and chemicals using several steps.
Which is cheaper, desalination or recycling? The USGS says desalination costs about twice as much as other sources at one major US plant. The Orange County district says recycling uses about one-third the energy of desalination.
Why not desalinate everywhere? Cost, energy and environmental concerns such as brine and marine life, according to the USGS.
Information checked on: November 13, 2026. Plant capacity and costs change, so check current sources.
Sources
- US Geological Survey, Water Science School, “Desalination” (September 2, 2026)
- US Environmental Protection Agency, “Basic Information about Water Reuse”
- Orange County Water District, “GWRS: new water you can count on” (ocwd.com/gwrs)
- World Health Organization, “Drinking-water” fact sheet (September 13, 2023)
