Image from Freepik
From Transboundary aquifers in Mexico by Gonzalo Hatch Kuri
Groundwater, aquifer, is a component of the hydrological cycle and is in motion; it is not a “reservoir”, nor is it “stored”, it flows within the cycle.
Of all the freshwater available on Earth, 97% corresponds to groundwater and 3% to surface water (lakes, swamps, rivers).
Physically accessible quantities of freshwater in the world
| Glaciers, perpetual snow and permafrost | 27 760 000 000 km3 | 69.40% |
| Groundwater | 12 112 000 000 km3 | 30.28% |
| Surface water | 128 000 000 km3 | 0.31% |
| Total fresh water | 40 000 000 000 km3 | 100% |
Source
Rivera, A. (2015). Transboundary aquifers along the Canada–USA border: Science, policy and social issues. Journal of Hydrology: Regional Studies, 4, 623-643.
