How many aquifers around the world are running out of water
An aquifer is an underground layer of rock or soil that holds water people can pump up through wells. A 2024 study in the journal Nature checked groundwater levels at about 170,000 wells across 1,693 aquifer systems in more than 40 countries, the largest such count ever assembled. Levels fell more than a tenth of a meter a year in 36% of those systems between 2000 and 2022, the study found. That is the current, sourced answer to how many aquifers around the world are running out of water, and it rests on a far larger and newer sample than an older 2015 study of just 37 aquifers. Inside that 36%, a smaller group, 12% of every aquifer system studied, is falling especially fast, more than half a meter a year.
The study reports those 2 shares, 36% and 12%, as overlapping totals, with the fast declining group nested inside the wider declining group, not as 2 separate counts that add up. Subtracting the fast group from the wider decline count gives 407 aquifer systems, out of the 1,693 studied, declining at a moderate pace, and subtracting the full declining count from the total gives 1,076 systems that stayed stable or rose over the same period. Both subtractions are arithmetic MAOWCE ran on the 2 numbers the study itself published, so the chart below counts every one of the 1,693 systems exactly once instead of repeating the 210 fastest decliners inside a second, larger bar.
MAOWCE calculated the moderate and fast rows by subtracting the overlapping 36% and 12% totals the study itself published, so these 3 rows are mutually exclusive and add up to the full 1,693 aquifer systems studied, rather than repeating the fastest decliners inside a second bar.
Show the numbers
| Stable or rising | 1076 |
| Declining moderately | 407 |
| Declining fast | 210 |
Why a falling water table matters beyond farming
Groundwater is the water held in these aquifers, and it makes up 99% of all the liquid freshwater on Earth, the United Nations World Water Development Report 2022 states. It supplies half of all the water the world withdraws for drinking and other home use, and around 25% of the water it withdraws for irrigation, growing food with water pumped or piped onto fields, the same report states. Nearly half of the global urban population is believed to depend on groundwater, the report also finds. A falling water table under a city or a farming region therefore threatens supply that half the planet already leans on for the water that comes out of a tap or reaches a crop.
All 3 shares come from the same 2022 United Nations report on groundwater.
Show the numbers
| Share of all liquid freshwater on Earth | 99 |
| Share of water withdrawn worldwide for drinking and other home use | 50 |
| Share of water withdrawn worldwide for irrigation | 25 |
What a declining aquifer looks like on the ground in the United States
About half of the United States population gets its drinking water from groundwater, and nearly all of the rural population does, the United States Geological Survey states. The country pumps more than 50 billion gallons of groundwater a day for agriculture. Total United States groundwater depletion reached approximately 1,000 cubic kilometers between 1900 and 2008, and the pace nearly tripled by the end of that window, from an average of 9.2 cubic kilometers a year across the full century to almost 25 cubic kilometers a year just between 2000 and 2008, the agency reports. Measured declines in named regions run deep. The High Plains aquifer has fallen more than 100 feet in some areas, parts of Arizona have fallen 300 to 500 feet, and the Chicago and Milwaukee area has fallen as much as 900 feet since 1864.
Not every aquifer studied is getting worse. In 16% of the 1,693 systems the 2024 study checked, an earlier decline reversed into a later rise.