From your description of the water issues, I presume the house has a crawl space. Couple of suggestions come to mind, 1) to check if there is any active plumbing leak in the house, close all water outlets and see if the water main meter needle spins. If the needle spins, there is some water leak that needs further investigation 2) it is also possible with the recent rains and bad drainage around the house, the water could have collected under the crawl space.

IMO it is also a good time to check the attic for any roof related leaks. Good luck with your purchase.