The South Pacific islands of Tuvalu, Tokelau and Samoa are experiencing a water shortage so severe that most residents are left with only a week’s worth of bottled water to drink, the Associated Press reports.

What a water shortage looks like in Manila. (Bullitt Marquez/Associated Press)

As the world’s population grows, putting more pressure on our water supply, and the supply of freshwater is reduced by pollution and contamination, more countries are forced to deal with extreme shortages of water.

The water shortage in the South Pacific can be blamed on a severe lack of rain and the mixing of the region’s freshwater reserves with saltwater from rising seas scientists blame on climate change.

Desalination machines and Red Cross-supplied bottled water have kept the several thousand people on the three islands from going thirsty so far. But Red Cross team leader Dean Manderson told the AP that the situation is becoming “quite dire.”

A recent report by Web site Our Amazing Planet gives some insight into why islands such as Tuvalu, Tokelau and Samoa can experience this kind of shortage.

“If Earth was the size of a basketball, all of its water would fit into a ping pong ball,” the Web site says. “If the Earth was an apple, the water layer would be thinner than the fruit’s skin.”

That’s counting both fresh and salt water. Although 72 percent of Earth is covered in water, 97 percent of that is salty ocean water we cannot drink. And just six countries — Brazil, Russia, Canada, Indonesia, China and Colombia — control 50 percent of the world’s freshwater reserves.

It’s not hard to understand, then, why as waters continue to rise and pollute the freshwater left on Tuvalu, Tokelau and Samoa, officials say life on the islands looks increasingly precarious.