My in-laws have an active oil tank in their backyard. I wanted to see what could be done to protect their interests and found that, as a result of the Heating Oil Pollution Liability Act of 1995, a fund is available in Washington to cover the cost of leaks and other environmental damage up to $60,000 This program is available to owners of registered residential oil tanks only, and does not cover pre-existing oil leaks. More information is available at the Pollution Liability Insurance Agency.
The Real Property Transfer Disclosure Statement, which most sellers of residential property in Washington are required to complete, specifically asks the question: "Are there any tanks or underground storage tanks on the property?" In most instances, the existence of fuel storage tanks must be disclosed prior to transferring property. Many times I see the 'No' box checked when the seller really doesn't know, which is why I, personally, don't always trust the answers given.