Most of the underground tanks associated with private residences and farms are used as storage for furnace oil or gasoline. When you are looking at investment properties, you'll find some buried tanks that are in service and others that have not been used for some time.

Residential storage tanks holding less than 1,100 gallons are not controlled by the federal underground storage tank program, but they can still be a problem — particularly if they are no longer used. Buyers worry that a tank will leak its contents into the soil or rust away and cause a cave-in of the surrounding earth. They often want storage tanks removed prior to closing, which means the seller has to pay for it. If the tank has already leaked fuel into the ground, buyers certainly don't want to pay to clean up the spill.

If buyers do agree to leave a tank in place, they usually ask for a reduction of the property's sales price to compensate for removing the tank later. The reduction they ask for is typically quite a bit more than the actual cost of removing the tank. Solve that problem by getting rid of the storage tank before you put the property on the market.

Removal is the best solution, but empty tanks can sometimes be filled with a special concrete-like mixture and left in place. The EPA Web site offers information to help you determine if filling a tank makes sense for your situation.

The hazards mentioned in this chapter are common, but they are not the only hazards you will encounter. Some areas have problems with pesticide residue that's entered private wells; other are plagued with high levels of arsenic in the soil.