J. Tariq,

You may want to take a look at the link below.

https://wood-energy.extension.org/water-quality-and-quantity/

Sorry Aristidis Matsoukis

There is also a vast amount of water bound in rocks.

https://www.nextbigfuture.com/2016/11/there-are-stable-hydrous-water-bearing.html

https://www.sciencedirect.com/science/article/abs/pii/S0024493716301360

https://news.northwestern.edu/stories/2014/06/new-evidence-for-oceans-of-water-deep-in-the-earth

https://phys.org/news/2014-06-evidence-oceans-deep-earth.html

https://newatlas.com/freshwater-reserves-under-sea/30072/

https://interestingengineering.com/culture/huge-freshwater-aquifer-has-been-found-under-the-atlantic-ocean

https://phys.org/news/2015-11-earth-hidden-groundwater.html

https://www.seeker.com/giant-mysterious-body-of-water-found-under-china-desert-1770240358.html

Regards,

Joachim