Residential & Heating Oil Tanks

storage tank

What if I am no longer using heating oil to heat my home?

Many Washington State residents have switched from oil to natural gas or electricity as a means of heating their homes. Sometimes when this happens the home owner doesnot know how to properly deal with the "unused" heating oil tank. Neglecting to take care of an unused tank can cause serious problems for the home owner. For instance:

Tanks can develop holes and release heating oil into the soil. The released
oil can contaminate groundwater, surface water, storm sewers, and cause
vapor problems in nearby buildings. Under the state Model Toxics Control Act,
the tank owner may be held liable for damage caused by a leaking tank.

Neither the federal government nor Washington State regulates the use or operation of residential heating oil tanks. However, some local governments have requirements or guidelines for closing and removing these tanks. Before you remove your tank, talk to your local Fire Marshal and city or county building department. Ask American Distributing Co. about permits, inspections, or other requirements that may apply to residential heating oil tank closure or removal. Regulations and policies vary from place to place and may change from time to time.

  • Corrosion can cause underground tanks to deteriorate, making cave-ins
    a possibility. The home owner could be held liable for injuries caused by a cave-in.
  • Before finalizing the sale of a house, lending institutions and home buyers may
    want sellers to remove or "close" unused heating oil tanks. To "close" a heating
    oil tank, the home owner has the tank cleaned out and filled. The tank is then
    left buried in the ground.

The rest of this report contains some commonly asked questions about residential heating oil tanks and the Department of Ecology's answers to those questions.


What should I do if I have an unused heating oil tank on my property?

1. Find out what's in the tank.

Most underground residential tanks are easy to find. If you have trouble locating your tank, try following the fuel lines from the house, locating the tank vent pipes, or use a hand probe or metal detector.

To find out if there's still oil in the tank:

Remove the filler cap.
Insert a long stick into the tank until it touches bottom.
Remove stick - If there is oil in the tank you will be able to see it on the stick.

Sometimes a tank will contain oil and water, or primarily water (the water will settle to the bottom, the oil will float on top). You can check for water by putting a small amount of water- reactive paste on the end of the stick and inserting the stick into the tank. If there is water in the tank, the paste will turn color. The paste can be purchased from American Distributing Co.

2. Have all unused heating oil removed from your tank.

The Department of Ecology strongly recommends that you have all unused heating oil removed from your tank. Removing the unused oil is the easiest, least costly, and single-most important action you can take to prevent contamination of soil and groundwater. After the heating oil has been pumped out of your tank, you should think about having your tank removed or "closed in place."

NOTE: If you have an unused heating oil tank, do not re-fill it unless it has been checked by American Distributing Co., and never put household waste like paint, antifreeze, or used motor oil into an unused residential heating oil tank.

Have your tank removed

The Department of Ecology recommends that you have the tank removed because:

a) If the tank has leaked, it will be easier to find and clean up any contaminated soil.
b) Often, home buyers and lending institutions require assurance that the property 
is not contaminated before agreeing to complete property transactions. The bestway to provide that assurance is to remove the tank and sample the soil in the pit.

Tank removal allows visual inspection of the area under the tank and more accurate soil sampling. Remember to keep reports of tank removal and soil samples for your records. Below are some of the activities American Distributing Co. will probably do when removing your tank.

Pump all remaining oil from your tank.
Clean out any sludge in the bottom of the tank.
Excavate down to top of tank.
Remove or cap all lines.
Remove potentially explosive vapors from the tank.
Remove the tank from the ground.
Properly dispose of the tank.

Have your tank "closed in place"

This is a popular option for residential tanks - especially if removal isn't possible. But before choosing this alternative, consider the future of your property.  Potential buyers or lenders may require you to remove the tank, and a filled tank is harder to remove (unless it has been filled with foam).  Below are some activities American Distributing Co. will probably do when closing your tank in place.

1. Pump all remaining oil from your tank.
2. Clean out any sludge in the bottom of the tank.
3. Remove or cap all lines.
4. Fill the tank with inert solid material, such as a weak cement slurry and sand.
5. Plug or cap all openings in the tank.
6. Backfill the hole.

How can I find a company or contractor to do my tank work?

Many companies provide services for residential heating oil tanks. Some companies provide pumping, cleaning, filling, removal and disposal services and some specialize in one or two services.

American Distributing Co. is a company that will pump and clean your tank or fill or remove your tank. The Department of Ecology recommends that you hire an experienced person to do the work.  Our employees have "Hazardous Material" certificates and issue "Tank Decommissioning" certificates.

How much does it cost to have tank work done?

The cost of tank services will vary depending on the size, location, and accessibility of your tank. Costs can also vary among companies performing the same services. Ask American Distributing Co. for an itemized estimate. Estimates are usually free. Ask what the charges will be and how they will be determined.  Below is some additional information about tank services:

  • Pumping and Cleaning: Sometimes charitable organizations sponsor
    programs to donate oil to low-income residents. American Distributing Co.
    will pump your oil for a minimal fee. To find out if there is such a program in 
    your area, call 1-800-RECYCLE or check with American Distributing Co.
    at 1-800-579-6777, 360-658-3751 or 425-252-2126.
  • Filling: The cost of filling the tank depends on the type and amount of fill 
    material your contractor uses.
  • Removal/Disposal: You may be able to save money by having one company
    perform several services at one time. Or you may be able to negotiate a price 
    break if several residences in the same neighborhood have services performed 
    at the same time.

Companies that clean tanks and/or recycle waste oil always have to consider the possibility that there may be hazardous substances in the waste oil or sludge. They must include testing and handling costs when filling or removing a tank, and that in turn affects your cost.

May I do the work myself?

While there is no law prohibiting you from doing the work, the Department of Ecology doesn't recommend doing tank removal yourself because of the potential safety risks. You should hire an experienced contractor to do the work.


Working on an underground heating oil tank can be dangerous. Under certain conditions these tanks can explode. Working in the excavation pit, cutting open or handling heavy tanks, and using power equipment also pose risks to the home owner. Never enter an underground storage tank, even if it has been cut open. The Department of Ecology recommends that you hire an experienced contractor to perform the work.

If you are currently using heating oil to heat your home

Many Washington State residents are still using heating oil to heat their homes. Unfortunately, most residential heating oil tanks are 30-50 years old, and nearing (or past) the time when they will begin leaking. Here are some tips on how to determine if your tank is leaking:

  • If your furnace seems to be using more fuel than usual, your heating oil tank 
    may have developed a leak. (Consider other possible factors for variable fuel 
    usage, such as unusually cold weather or furnace malfunction.)
  • Is there water in your tank? Stick the tank, using water-reactive paste on the 
    stick, to find out. A small amount of water is normal, but several inches may 
    mean water is getting in through a hole in the tank - which means oil could 
    be getting out.
  • During the summer, when you aren't using the furnace, carefully measure and 
    record the level of fuel in the tank. Make sure the furnace is completely off. 
    You may even want to disable it to be sure it isn't coming on at night. Wait 
    as long as possible, keeping the furnace off (preferably at least two weeks, 
    but the longer you wait, the smaller the leak you will be able to detect), then 
    measure the fuel again. If the level is down, the tank is probably leaking. If 
    the level is up, you should check to see if water is entering the tank, as 
    described above.
  • Check with American Distributing Co. about there services or programs 
    offered to residential oil heat customers. American Distributing Co. has programs 
    that provide warranty against leaks, insurance to cover cleanup costs, and/or 
    regular tank maintenance.

What shoul I do if my tank has leaked?

Knowingly using a leaking tank is negligence. If you discover that your tank is leaking you must take immediate action to stop the leak. The best first action is to have all heating oil pumped from the tank.

Leaks from heating oil tanks are usually discovered when underground tanks are removed, when vapors or heating oil seep into basements, or when heating oil levels drop faster than they should based on the amount of oil being burned.

In most cases where a tank has leaked, only the soil near the tank is affected. Sometimes, however, the heating oil may also have contaminated groundwater or surface water.

It is the owner's responsibility to:

  • evaluate the extent of contamination caused by the leak.
  • determine if it is a threat to human health and the environment.
  • clean up any contamination caused by the leak.

Shoud I report the leak to Ecology?

Minor Leaks

Minor leaks or spills from residential heating oil tanks do not have to be reported to the Department of Ecology. Minor leaks are those that affect only the soil near the tank.

More Extensive Leaks
If heating oil has gotten into surface waters, such as creeks, lakes, rivers, or storm sewers, you must report it immediately to the Emergency Management Division at 1-800-258-5990. If your heating oil has caused any of the following situations, you should report the leak to the appropriate Ecology regional office within 90 days.

  • The heating oil has reached adjoining properties.
  • The heating oil has affected a well or groundwater.
  • The heating oil has caused vapor problems in nearby buildings.
  • The heating oil has pooled on the surface of the ground.
  • The heating oil has caused extensive soil contamination.

NOTE: The Department of Ecology reserves the right to take future action in unaddressed or unreported situations, should the need arise.

Should I clean up contamination caused by my leaking tank?

Yes, you should clean up contamination caused by a spill or leak of heating oil. Leaks can pollute wells and streams, and the vapors can make you or your children sick.  If you have contamination, you will probably want to hire American Distributing Company. When the cleanup is completed, your cleanup contractor should give you a copy of the cleanup report and "Tank Decommissioning" certificate.

Should I send a copy of the cleanup report to Ecology?

Cleanup reports of minor leaks from residential heating oil tanks do not need to be sent to Ecology. Ecology does not track or report on these cleanups. The home owner should keep the written cleanup report for future reference by lenders and potential buyers.  Cleanup reports on more extensive leaks from residential heating oil tanks should be sent to the appropriate Ecology regional office (see Table 1). Ecology will keep track of and report on these sites.  Contact an Ecology Office for your region.


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