On the planet earth, most of the freshwater exists as ice caps and glaciers. Out of the remaining freshwater, the largest proportion

The distribution of Earth's freshwater is highly unequal. While approximately 97% of all water is saline, the remaining 3% is freshwater [3]. Of this freshwater, the vast majority (roughly 68.7% to 75%) is locked in ice caps and glaciers [4]. According to global hydrological data, groundwater represents the largest proportion of the remaining freshwater, accounting for approximately 30.1% of the total freshwater supply. In contrast, surface water sources such as freshwater lakes (0.26% to 0.7%), soil moisture, and atmospheric water vapor represent significantly smaller fractions [4]. Specifically, surface and atmospheric water combined make up only about 1.2% of total freshwater. Therefore, after ice caps and glaciers, groundwater is the most significant reservoir of freshwater on the planet.

Sources

1. [3] https://www.usgs.gov/faqs/how-much-earths-water-stored-glaciers
2. [4] https://gpm.nasa.gov/education/articles/earth-observatory-water-cycle-overview