Basement tank installations are very common.  Typically a single basement tank has a capacity of 275 gallons.  Homes requiring additional storage capacity may have two-275 gallon tanks tied together, side by side. 

A properly installed basement tank will have the following features.  (Click Here: to view a diagram showing a basement tank installation.)

Outside fill pipe and vent pipe should be sloped toward the tank.  Vent pipes sloped away from the tank can form a "trap" of oil causing fuel to spray outside during the filling process.  Vent pipes also must be clear of any debris... i.e. dirt, rust, nests, etc.  Restricted vents cause air pressure to build up in the tank during filling and will "blow-back" oil through the fill and vent pipes.

Vent alarm (whistle) should be installed in all vent pipes.  Since basement tanks are not visible to a fuel oil deliveryman, these tanks represent a unique risk when filling them.  A vent whistle is installed in the top of the tank in the vent opening.  During the filling process, as air escapes the tank, the whistle sounds.  When the tank is nearly full, the whistle becomes submerged and the whistle stops.  Required by law in some states, this simple device serves two very important purposes.  First, it confirms to the deliveryman, that there is indeed a tank in the basement receiving fuel.  Second, it signals when the tank is nearly full and prevents fuel from reaching the top fittings in the tank.  If fuel reaches these top fittings (i.e. tank gauge)  and they leak, then you have a smelly mess.  Without a vent whistle, the only indication that the tank is full is when the deliveryman hears fuel gurgle up in the vent pipe.  By this time, the fuel level is above the top of the tank.

Special Note:  If for any reason your basement tank is removed.  You must remove the fill and vent pipe completely, or plug them on the inside to prevent an accidental delivery of oil into your basement.  And, notify your supplier.