If you have to make a concession to buy a house inside your budget, that's one thing. You can take that risk if inclined. But decommissioned doesn't mean it wasn't leaking, and you're on the hook for soil remediation (ludicrous amounts of money) if you buy the house and it's found that there is soil contamination. If you can, demand the seller have it removed entirely and the soil underneath it tested. That's a hairy situation in itself and they probably won't agree to it, at which you should just walk away. I don't know if the option exists or if you're desperate enough, but ask if they will have it removed and add some of the expense to the sale price provided the soil test comes back clean. Other houses are out there and even more will show up if you can wait. I personally wouldn't take the risk, especially not with the current house prices.