Foreclosures are generally sold "as is" with the bank unwilling to make any repairs. (Banks will also insist that New York City and New York State transfer taxes - which are normally paid by the seller - be paid by the buyer.)
If you have not signed a contract then you may wish to have the tank or soil tested at your expense. Based on the results, you could renegotiate your price or walk away from the deal.
Coldwell Banker Residential Brokerage
When buying from banks/lenders they put all costs in to the buyers pool. And generally the properties are As-Is-Bassis. So im pretty much sure you will hv to take care of it.
Any resultant offer could be inclusive of the cost to repair/replace said tank if needed or perhaps a credit at closing. What's the worst that can happen? They ignore you? They counter? If all your ducks are in a row and it makes sense, they may bite. Good luck.