Instead I will just recommend two things to anyone dreaming of buying a house. Start watching This Old House, [especially] the back catalog. Almost everything that can go wrong on a house has gone wrong there. And remember this while watching it:
Intelligent people learn from their own mistakes, while wise people learn from the mistakes of others.
The “cat litter” crack about bentonite clay: bentonite is nearly the only way people discuss for building an artificial pond if you don’t want to use a synthetic liner. But you don’t get a pond by sealing half of the hole you dug (and it takes a lot of clay). The water just runs out somewhere else. Or in this case, in.
Edit: Old TOH > New TOH