Some 45 corporate chiefs attending the Rio+20 conference on sustainable development on Monday pledged to make water security a strategic priority and called for decisive action by governments.

Speaking on behalf of the 45 CEOs, Igal Aisenberg, chief executive of Israel's Netafim micro-irrigation company, urged concerted action by governments, the private sector, civil society and others "to tackle the global crisis in water access, quality and sanitation."

Committing to water sustainability were chiefs of global companies such as Pepsico, Coca Cola, Nestle, Saint-Gobain, Royal Dutch Shell, Akzo Nobel, Bayer, Heineken and Pernod Ricard.

All have endorsed the UN Global Compact's CEO Water Mandate initiative launched by UN chief Ban Ki-moon in 2007.

In a statement addressed to the Rio+20 leaders due to debate sustainable development here from Wednesday to Friday, the 45 executives urged them "to take decisive actions during and after this summit on one of our world's great challenges -- water."

"Problems related to water availability, quality and sanitation are undermining development in many regions of the world - exacting an enormous human cost while also undermining critical life-giving ecosystems," they said.

Roughly 800 million people around the world lack access to safe drinking water, and 2.5 billion lack basic sanitation," according to the United Nations.

The UN also estimates that two thirds of the world's seven-billion-strong population will face water scarcity by 2025.

Adrian Sym, executive director as the Alliance for Water Stewardship, hailed the CEOs statement "as an act of leadership by the private sector".

"The problems are so vast that governments alone cannot solve them," he added, stressing that cross-sectorial leadership was a critical piece in solving the problem.

Robert ter Kuile, a senior executive at Pepsico, said water was critical to "our entire value chain" and reaffirmed his company's goal of "a 20 percent reduction (in water usage) per unit of production in (its) operations by 2015."