The United Nations said it has received support from chief executive officers at 45 companies, from Levi Strauss & Co. to Coca-Cola Co., in an effort to work toward making water use more efficient.

The companies will join the U.N. Global Compact in committing to improve water-management practices, during a meeting in Rio de Janeiro Monday. The compact is the world’s biggest organization backing sustainability measures.

About 800 million people worldwide don’t have safe drinking water and another 2.5 billion lack access to sanitation, the U.N. estimated. It cited research from McKinsey & Co. showing water demand will outstrip supply by 40 percent by 2030. 

“Water is a critical issue, and most companies are doing nothing about it,” Gavin Power, deputy director of the U.N. Global Compact, said in an interview in Rio de Janiero Sunday. “This is a market failure.”

Levi Strauss is working to ensure cotton growers who supply materials for its jeans are using water efficiently, and Coke reduced the amount of water it takes to make a 1-liter product by 13 percent in 2011, according to the U.N.

Other companies participating in the program include Anheuser-Busch InBev NV, Banco do Brasil SA, Bayer AG, DeBeers Group, Dow Chemical Co., Nestle SA, Royal Dutch Shell Plc, Unilever NV and Xstrata Plc.

“All companies are water companies because they all rely on water, whether it’s in pharmaceuticals or for beverages,” Power said. “The scale of the water problem is so big that governments can’t solve it alone. They need the help of the private sector.”

The U.N. announcement will be made in Rio de Janiero, where 50,000 delegates and 130 heads of state have gathered for the Rio+20 conference on sustainable development. The U.N. and other organizations are hosting conferences across the city. 

(Bloomberg)