A majority of the world's major water sources are being depleted faster than they can be refilled

The world is running out of water.

New NASA satellite data shows that a majority of the world's largest underground aquifers - the predominant source of our drinking water - are being depleted faster than they can be refilled.

From its recent 2003-2013 study, NASA concluded that 21 of the 37 largest aquifers (underground reservoirs that store groundwater from rain and snow) are running out too fast to be replenished. An additional 13 are declining at a rate that puts them in a category NASA calls the "most troubled."

Here's a map from the report showing the 37 largest aquifers in the world and their state of depletion. Red indicates aquifers that are being depleted faster than they can be replenished (in millimeters). Cream indicates aquifers that have remained relatively stable, and blue aquifers are in good shape:

Water Resources Research

This is extremely troubling considering that we draw about a third of the world's water from aquifers.

"The situation is quite critical," Jay Famiglietti, senior water scientist at NASA's Jet Propulsion Laboratory in California and principal investigator of the University of California Irvine-led studies, told the Washington Post.

NASA gathered their data using special satellites called Gravity Recovery and Climate Experiment satellites, which took precise measurements of the world's groundwater aquifers. Since the bigger, heavier water sources exerted a stronger gravitational pull on the satellite, they could use this data to spot the largest sources of water.

AP Photo/Jae C. Hong, File

Irrigation water runs along a dried-up ditch between rice farms to provide water for the fields in Richvale, Calif.

Should we have seen this coming?

The depletion of water around the world, while alarming, shouldn't come as any surprise. Every Little Drop, an organization devoted to water conservation, said that between 1900 and 2000, worldwide water use increased six-fold, and the United Nations expects the situation to get "considerably worse" by 2030.

Bank of America Merrill Lynch reports that water scarcity is our biggest problem worldwide.

At present, droughts are happening on every single continent in the world, save Antarctica, reports the Global Drought Information System. In the US, drought-stricken California is currently drawing 60% of its water from aquifers.

Why it's likely to get worse

Two aquifers in America, including California's Central Valley Aquifer and one that stretches across the southeast coast of Florida are also unsustainable, the Post reports. According to the US Government Accountability Office , 40 of 50 states have at least one region that is expected to face some kind of water shortage within the next 10 years.

Here's a map of the amounts of water used domestically in each state, with dark blue being the most and light blue being the least:

U.S. Geological Survey

Underground drilling for natural resources like gold, iron, and oil has put added stress on the aquifers, the Post reports, and the top three fastest depleting aquifers are all located in the Middle East.

This is compounded by the fact that climate change has dried out regions of the US along the equator and caused areas further north and south to experience heavier rainfall.

Famiglietti says this creates a self-reinforcing cycle where people who live closer to the equator pump more water from aquifers due to drier conditions, but once that water is removed from the ground it evaporates and is redistributed as rainfall to areas further north and south, meaning the aquifers that are hurting for groundwater cannot get replenished.