Caring For and Replacing Your Heating Oil Tank

Posted by Steven Zweig on August 2, 2009 at 7:08 pm

An indoor, above-ground tank installed in a basement. Oil tanks should not be mounted too close to a furnace, boiler, or oil heater. Home heating oil is a very safe fuel, but putting any fossil fuel next to a flame is not recommended. (image: inspect-ny.com)

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On average, a home heating oil tank lasts 15–30 years. However, the consequences of a leak you don’t catch are serious; therefore, once a tank hits 15 years, you should make sure to get it inspected regularly—and consider replacement if any problems crop up, during inspection or otherwise.

Oil Tank Facts

There are two kinds of home heating oil tanks: underground and aboveground. An underground tank is buried in your yard and typically holds 550–1,000 gallons of oil.  An aboveground tank is installed in your home and generally comes in 275 or 330 gallon sizes.

Given that aboveground tanks hold less fuel and take up valuable room in your home, underground tanks would seem to be more desirable. However, the opposite is usually true: an aboveground tank has significant advantages in ease of installation, inspection, maintenance, and, if necessary, repair and removal. Installing or replacing an aboveground tank is major construction, similar to installing any major appliance

What about installing an aboveground tank outdoors, such as next to or behind your home? You can do this, but shouldn’t if you have other options. First, water is the great enemy of oil tanks—since they are generally made of steel, they are subject to rust and corrosion. An aboveground tank is exposed to rain and snow and is more vulnerable to corrosion.

An outdoor tank that has fallen victim to rust and corrosion. (image: inspect-ny.com)

Second, heating oil is affected by temperature. Number 2 fuel oil (the most common grade of home heating oil) will start to cloud with wax crystals, as well as thickening, when the temperature gets below 20 degrees Fahrenheit. This will impede the flow of oil through your heating system and, as the temperature drops further, oil could stop flowing completely.  If you want to install an outdoor tank—or already have one—a good precaution would be to install an enclosure (sometimes called an “oil shed”) around it. These enclosures will protect the tank from the elements, while also serving as an emergency or secondary containment system for any spilled or leaking oil.  And do not install an indoor tank outside—they are not designed to withstand exposure to the elements.

An outdoor heating oil tank stroage unit. (image: whitesplumbing.com)

Consequences of an Oil Leak

First, the good news: you don’t need to worry too much about an explosion. Unlike natural gas or propane, home heating oil is generally not explosive. Home heating oil must be converted to a fine mist and mixed with air in the right proportions to burn efficiently, let alone explode. (Natural gas and propane, being gases already, will much more easily turn into an explosive mix when exposed to air, which is why a home gas leak is an occasion for vacating the premises and calling the fire department.)  However, there are consequences. The more obvious ones are staining and loss of oil that you paid for—if you allow an oil leak to go unchecked, you may as well start burning dollar bills for warmth. The more serious consequences, however, are environmental. Heating oil can contaminate soil, groundwater, and also nearby streams, ponds, rivers, and lakes. Because oil is itself a liquid, it will flow to the o the same places that water does; even a very small leak can contaminate drinking water resources over time.

That is what creates the potential for an enormous expense in the event of an underground oil tank leak: not only does the tank have to be removed, but contaminated soil has to be removed as well. You could end up excavating a large portion of your yard.

A conservative estimate of the cost to clean up after an underground oil tank leak is $20,000, and it only goes up from there: $50,000 is not uncommon, and one Canadian resident recently had to pay over $160,000 dollars to remove a long-buried, and long-leaking, oil tank from her property! (That was Canadian dollars, but would still equal around $132,000 USD.)