Most often unless the seller disclosues such circumstances, we, agents, have no way of knowing. where such things as water damage "come from." You can request a "seller's disclsoure" but since this is a foreclsoure property, I am afraid that you are on your own in determinging its origination. Perhaps having a home inspectection be a certified inspector MAY provide you with a little more insight.
Love and Peace,
Francesca, ePro, SRES