In the hydrological cycle, ocean water has the largest storage without doubt. However, our estimates of the ocean water storage have great uncertainty. I have done some preliminary research into this field and I’d like to share my understanding of the current state of these estimates. I also post a related question in the ReseachGate website (Link).
I will start with a few publications and reports. The first one is the USGS website:, which states the ocean storage to be around 96.5% of the global storage. The numbers are from “World fresh water resources” by Peter H Gleick 1993.