Starting to sound like the resource generation from the rimworld game but yes it does sounds great, though might be difficult.
Would first need a scanning machine that would most likely work like a radar but if it comes across one of these underground water caves it would mark it on a map in either a resource like way or some other way and then comes the question whether these underground pools should also slowly refill themselves like an ocean.
And finally should they be re-watered-able? As in should you be able to pump down water (or maybe some other fluids) as a way of storing them, I think this would go too much into crazy territory but it would be fun