CNN  — 

A quarter of the world’s population is living in regions of extremely high water stress – with “once unthinkable” water crises becoming common, researchers have said.

With the climate crisis biting, 17 countries – home to one in four people on the planet – are deemed to be “extremely high water-stressed,” meaning they are now consuming more than 80% of their available water every year, the World Resources Institute (WRI) has revealed in a report.

And the growing shortages are fueling the risk of conflict in such countries, concentrated in the Middle East and North Africa, the researchers say.

Paul Reig, director of WRI’s Aquedact water risk project, told CNN that the high level of demand relative to supply in these areas “puts huge pressure on available water resources and poses a threat to agricultural, industrial and domestic water users that rely on it.”

Qatar is ranked as the world’s most water-stressed country, followed by Israel and Lebanon, Iran and Jordan. In Africa, Libya and Eritrea are suffering the worst shortages.

“Twelve out of the 17, extremely high water stressed countries are in the Middle East and North Africa,” Reig told CNN. “The region is is naturally dry and arid. But the situation there is getting worse. There’s a number of reports and research pointing to the fact that water stress can exacerbate both migration and conflict, and that water is currently a source of growing tension and violence in the Middle East,” Reig said.

Experts also warn that such a narrow margin between supply and demand could push countries towards more “day zeroes” – extreme water crises that threaten to see taps running dry, a situation that Cape Town came to the verge of last year.

“Water stress is the biggest crisis no one is talking about. Its consequences are in plain sight in the form of food insecurity, conflict and migration, and financial instability.” said Andrew Steer, president and CEO of the World Resources Institute.

In June, Chennai became the first major Indian city to face an acute water shortage. India, ranked 13th in the world for water stress, has more than three times the population of the other 16 countries in the “extremely stressed” category combined.

Even in countries with low water stress overall, individual areas could still experience extreme water stress. The USA ranks 71st on WRI’s list, but the state of New Mexico is classed as experiencing extremely high stress levels.