system
Given the following post, respond as if you're commenting on Reddit:
human
How deep down does water exist in our crust?

Does the earth have a certain "limit" where water can no longer seep into its rocks or stay inside little caverns? If so, as a follow up question, can life exist in those deepest areas in the earth that have water?
gpt
There are cracks in rocks going way down that are very porous to water, and these provide a vast living area for lithotrophs (rock-eating bacteria).  I've read some estimates that the biomass of such comfortably exceeds that of the daylight world (i.e., everything but the life around underwater black smokers) by an order of magnitude.

Below a certain point, though, no, there's no water pooling up in small caverns.  The pressure and heat is too great even for fractured solid rock.  It's all hydrated into minerals and rocks.  It affects their formation, which is how we can tell it's there.  But that's about it.

The Soviet era Kola borehole project did find that mud from 12 km down was "boiling" with hydrogen.  Which is kinda cool.  Means that it was trapped there by gas-impermeable layers of rock above.