FACTBOX: Key facts on the world's water supply

(Reuters) - Government ministers and scientists meet in Istanbul this week to discuss how to better manage the world's water supply, improve access to sanitation, and avoid catastrophic floods and droughts.

The United Nations warned last week the world must act urgently to avert a global water crisis that is expected to worsen with climate change.

Following are some facts and figures about the world's water:

-- There are 1.4 billion cubic kilometers of water on the planet but almost 97 percent is salt water. Most freshwater is locked up in glaciers or deep underground, leaving only a fraction available for human consumption or use.

-- Most experts believe there is still enough water to go round, but its distribution is uneven. According to the Pacific Institute for Studies on Development, Environment and Security, North Americans have access to over 6,000 cubic meters per person per year stored in reservoirs. But the poorest African countries have less than 700 and Ethiopia has less than 50 cubic meters per person per year of water storage. Wealthy but water-scarce countries such as Saudi Arabia can afford expensive desalination projects, but poor ones cannot.

-- Agriculture accounts for 66 percent of human water consumption, industry 20 percent, domestic households 10 percent, according to the World Water Council. About four percent evaporates from man-made reservoirs.

-- Providing clean drinking water to the poor is one of the biggest development challenges. The United Nations Millennium Development Goals pledged at the start of this decade "to halve, by 2015, the proportion of the population without sustainable access to safe drinking water and basic sanitation." The U.N. says that since 1990, 1.6 billion people have gained access to safe water. But nearly a billion people still lack safe drinking water.

(Sources: Reuters, World Bank, International Monetary Fund, United Nations, Pacific Institute for Studies on Development, Environment and Security, World Water Council)