Preventing Spills from Home Heating Oil Storage Tanks


Aboveground Storage Tank Failures

On average, the Maine DEP responds to 1.5 spills every day from home heating oil tanks alone. Will your tank be one of them?

There are approximately 400,000 home heating oil (HHO) tanks in Maine. Many of these tanks meet the DEP “high risk” criteria and are in need of replacement to prevent spills. Heating oil spills can cause long term pollution in your drinking water and the air in your home, decrease the value of your home, and cause ecological damage to the surrounding environment. These preventable spills have resulted in millions of dollars spent on associated clean-up costs and have disrupted thousands of lives and homes. Is your tank a “high risk” tank? Find out here.

I have a spill or a leak! What should I do?
Please call DEP's 24-hour spill reporting hotline: (800) 482-0777

Help is available to all owners of aboveground oil storage tanks with spills or leaks that affect the environment through the Ground and Surface Waters Clean-Up and Response Fund.

How can a heating oil spill impact your home?

If a spill occurs within 300 feet of your well, within 300 feet of a neighbors well, or within 1000 feet of a public water supply, you or your community’s drinking water may be at risk of contamination. Remediation and water treatment can be costly, and in some cases, a new source of water is needed altogether.

A leak or spill can also contaminate the soil, even if the tank is on a concrete pad or in a basement. Contaminated soil can be a health hazard to those who come into contact with it and presents additional risks of polluting water supplies or indoor air.

A leak or spill can penetrate building components, like walls and concrete slabs, and create long term vapor sources in a building. Vapor intrusion can occur when contaminated soil beneath a structure results in vapors migrating up through cracks and pores in the foundation and into the enclosed space of a home. These vapors are hazardous to inhale. Removal of contaminated material and installation of vapor mitigation systems can be intrusive and costly.

A spill at your home may require long term DEP involvement which is often disruptive and inconvenient for homeowners. Additionally, the presence of contamination may impact the marketability and resale value of your house due to the health risks mentioned above, remediation challenges, and stigma associated with contaminated property.

What causes a tank to leak or fail?

Heating oil tanks are commonly found in many single-family residences across Maine, as well as in multi-family, commercial, and public buildings. The causes of the majority of home heating oil spills fall under three main categories: tank corrosion, parts failure, and human error.

Tank diagram

Corrosion is the leading cause of spills from heating oil tanks at single family residences in Maine. Most often, corrosion is caused from the inside out. Over time, fine impurities in heating oil can cause water, sludge, and sediments to build up and slowly eat away at the steel at the bottom of a heating oil tank. It is very difficult to determine the level of corrosion within a tank by simply looking at it from the outside. Ultrasonic thickness testing can help to determine steel thickness, which can indicate whether significant corrosion has occurred.

Heating oil parts failure can result from age, corrosion, and damage sustained from weather events. Tanks that are not adequately supported can tip or fall over to cause a spill. Unprotected filters can break when struck, such as from falling ice or snow with exterior tanks or unstable stored goods near indoor tanks. Buried fuel lines that do not have secondary containment can corrode or break, allowing oil to escape over time and cause widespread, long-term damage. Broken whistles can result in overfills and over pressurization as delivery drivers rely on the whistle stop to signal a full tank.

Human error spill causes include tank overfilling, improper maintenance or repair efforts, and damage to fuel lines and parts due to human activity (for example, stepping on fuel lines or oil filters).

How can you prevent your tank from leaking or causing a spill?

Replace your tank if it is approaching 25 years old or if it meets the “high risk” criteria

The best prevention method is to replace your tank if it meets the “high risk” criteria. The primary factor that pushes tanks into the “high risk” category is age – 25 years is the design life for heating oil tanks and the majority of tank failures occur in tanks that are 25 years or older. There are several other criteria that can increase the likelihood of a tank causing a spill. Find out if your tank meets any of the “high risk” criteria.

The Department recognizes that the cost of replacing home heating oil tanks can be significant. In order to help homeowners pay for the replacement of high risk tanks, the Department provides grants though the State’s nine Community Action Agencies (CAAs). If you are an income-eligible Maine resident, own your home, and have a high risk tank, you may be eligible for financial assistance to get your tank replaced. Contact your local CAA for more information.

Replace supporting tank equipment at risk of causing a spill

In cases where a full tank replacement is not necessary, but supporting tank equipment poses an imminent threat of causing a leak or spill, replacing equipment can be a simple and cost-effective solution. Work with a qualified professional to inspect supporting equipment such as fuel lines, filter assemblies, whistles, etc., to identify compromised parts in need of replacement. Maine homeowners may be eligible for up to $500 towards the cost of replacing ancillary tank equipment through DEP’s Home Heating Oil Equipment Replacement Project. Eligible ancillary tank equipment includes, but is not limited to, the following: fuel lines, vent whistles, gauges, filter protectors, and filters.

There are no income eligibility restrictions for this program. If you believe you have deficient ancillary tank equipment at risk of causing a spill, contact Racheal French to verify eligibility.

Get your tank inspected

Maine DEP recommends annual tank inspections, which can help identify tank issues before they lead to a leak or spill. For tanks under 20 years old, ultrasonic thickness testing can be an effective way to identify potential corrosion, which is otherwise unseen but is one of the most common causes of heating oil spills. To find out about service packages that offer an annual ultrasonic thickness test of your home heating oil tank, contact your oil dealer or service technician. If your tank is over 20 years old, it is time to consider a tank replacement or an alternative heating source.

Purchase a filter protector

Filter protectors are primarily used on outdoor home heating oil tanks to protect oil filters against damage from falling objects, such as falling ice or an unstable woodpile. However, they can also be used on indoor tanks to protect oil filters from anything that could fall or hit it to cause damage and possibly a leak. If you have an indoor or outdoor Granby tank (or similar tank type), you can purchase a filter protector. Learn more about filter protector options.

Prevent damage to buried fuel lines

Unprotected, buried lines can corrode, leading to an oil leak. Check to see if the line from your oil tank to the burner on your furnace or boiler that is buried in the floor of your basement has a sleeve on it. If it does not have a sleeve, then it must be replaced. Call your licensed oil burner technician.

Replacement lines can be run overhead or along the top of the basement floor if they are protected from physical damage. If you choose to run the replacement line overhead, have your licensed oil burner technician check the distance from the oil tank to the burner, the number of bends and curves in the line, and the capacity of the fuel pump on the burner to assure the pump is adequately sized for the length of run.

Some homeowners prefer the replacement line and sleeve out of the way and buried in the floor. This is usually done by cutting a small trench in the concrete floor, installing the sleeved replacement line in the trench, and then filling the trench with grout. In this case, make sure the sleeve is continuous and the ends of the sleeve extend 2” above the surface of the floor on both ends.

Surface view of an unprotected buried copper fuel line (left) and a properly protected (sleeved) buried copper fuel line (right)
Surface view of an unprotected buried copper fuel line (left) and a properly protected (sleeved) buried copper fuel line (right)
Below grade view of a leaking unprotected buried copper fuel line (right) and a properly protected (sleeved) buried copper fuel line (right)
Below grade view of a leaking unprotected buried copper fuel line (left) and a properly protected (sleeved) buried copper fuel line (right)

Consider alternatives to heating oil

If you are looking to remove or reduce the use of oil in your home, there are alternative methods of heating that may work for your home. Propane, natural gas, heat pumps, wood stoves, and pellet stoves are some examples of alternatives to heating oil. Visit the FAQ for more information on alternatives to heating oil, as well as available incentive and replacement programs.

Contact Us

Racheal French

David McCaskill

Additional Information

Frequently Asked Questions

Is your tank at risk of causing a spill? Take this quiz to see if your tank meets the “high risk” criteria.

Tanks Within Wellhead Protection Zones of Community Water Systems

Filter Protectors for Outdoor Tanks

Heating Oil Tank Safety with DEP Response Specialist, Lee Thomas

Related Programs

Community Action Agencies

Maine Fuel Board

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