Although it seems that humans and animals use most of the world’s water, heavy industry uses up to half of it. As a result, industries are looking for new ways to recycle water, especially in the face of increasing drought.

Some of the world’s most important industries, such as pharmaceuticals, food and beverages, textiles, mining, renewable energy and power, all use huge amounts of water. Now, new companies are finding ways to reclaim and recycle water as cost-effectively as possible.

According to Statista, the global water and wastewater treatment market is expected to reach half a trillion dollars by the end of this decade. Much of it is currently treated with harsh chemicals and uses a lot of energy, but companies like Xylem, Veolia and Boston-based startup Gradiant are trying to cut both costs and energy while eliminating chemicals.

“We take highly contaminated wastewater containing solvents, dissolved salt and organics and remove all the liquid waste,” said Prakash Govindan, co-founder and chief technical officer of Gradiant.

Anurag Bajpayee and Govindan founded Gradiant in 2013 as a spin-off of the Massachusetts Institute of Technology (MIT).

Gradiant’s technology mimics how nature creates rain. Wastewater is heated and pumped into a humidifier and mixed with ambient air. As they interact, the two substances are heated and vaporize, leaving the pollutants behind. Using proprietary technology, the vapor is passed into a column of cold, clean water. As the two substances mix, the air cools and fresh water drips like rain falling from a cloud. Gradiant says this process cuts traditional costs in half.

“Other technologies may recover 50 to 60 percent of the water, but we can recover 99 percent of the water,” Govindan said.

Gradiant is the first unicorn in the water treatment sector. Its customer list is impressive and includes companies such as Coca-ColaBMWs, Pfizer and Adnoc. The company claims to save 1.7 billion gallons of water a day, equivalent to the amount used by 48 million people. In the first half of this year, the company said it won new contracts worth over $500 million, making its growth trajectory attractive to investors.

“Scaling these technologies is hard. It’s easy to find a product, but it’s much harder to find a complete end-to-end solution for customers, and that’s exactly what Gradiant has done,” said Mark Danchak, co-founder of General Innovation Capital Partners, a Gradiant investor.

Gradiant is also backed by Warburg Pincus, M&G Investments, Formation 8, Clearvision Ventures and GRC. To date, it has raised $228 million.

CNBC producer Lisa Rizzolo contributed to this article.