Stanford's Solar Gel Pulls Drinking Water From Desert Air

One in four people on Earth lacks reliable access to safe drinking water, but researchers at Stanford and MIT just made a breakthrough that could change that using nothing but sunlight and air.

The team spent four years perfecting a sponge-like material called a hydrogel that pulls moisture from even the driest air and releases it as drinkable water. Made from lithium chloride salt and the same polymer found in diapers, the gel sits on a black-painted aluminum sheet that absorbs heat from the sun.

When the sun warms the material, it releases water vapor that condenses into liquid you can drink. The concept isn't new, but previous versions fell apart after just 30 uses, making them too expensive and unsafe for real-world use.

"Any degradation could make either the salt or the polymer go into the condenser," said Carlos Diaz-Marin, an assistant professor at Stanford's Doerr School of Sustainability. "That would basically destroy the potability of the water."

The team discovered the problem was the metal casing itself. Metal ions were sneaking into the gel and creating destructive radicals that ate away at the polymer chains like tiny scissors cutting through string.

The fix turned out to be surprisingly simple. They added a commercial anti-corrosion coating to block those ions, and suddenly the hydrogel lasted more than eight months and survived over 190 harvesting cycles without breaking down.

The team tested an earlier version in Chile's Atacama Desert, one of the driest places on Earth, using a cookie-sheet-sized panel. The current design produces about two liters per day, enough to meet one person's basic needs in an emergency.

The Ripple Effect

This improvement could drop the cost of produced water to about one cent per liter. That's roughly 1% of what bottled water costs and approaches what Americans pay for tap water from the tap.

"We see a path to this technology to perhaps even being competitive with tap water," Diaz-Marin said. His ultimate goal is five liters per day to ensure people in rural, arid regions where desalination isn't an option have all the water they need.

The team published their findings in Nature Communications in May 2025. While the technology isn't ready for large-scale use yet, Diaz-Marin said they're working quickly to make it available to communities that need it most.

For people who currently walk hundreds of hours per year to find water, this solar-powered solution could provide a reliable source right where they live.