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Leaky Heating Oil Tanks - How Oil Tanks are Tested for Evidence Leaks, of Current or Previous Oil Spills
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• Oil tank testing method choices
• Soil testing for oil tank leaks
• Tank pressure testing for oil tank leaks
• Simple tests for water in oil tanks
• Electronic scanning, other tank testing methods
• Ground scanning radar for hidden oil tank location

This document describes the common methods used to test oil storage tanks for evidence of leakage, either by soil testing, pressure testing of the tank, or by other tank screening measurements. Other steps to locate and test heating oil storage tanks at properties, both buried tanks and above ground tanks are discussed at other documents at this website. . Leaking oil tanks are not only a concern as contaminants of the water supply, but have become an increasing general environmental concern addressed by the DEC. Leaking commercial equipment and even simply-suspect equipment have been extremely costly to address. Such burdens were never anticipated when the equipment was installed. While similar regulations pertaining to residential installations are scarce, this topic is of growing concern to home owners and home buyers. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use the links at page left to navigate this document or to go to Other Website Topics. Green links at left show where you are in our document & website.

TANK TESTING - How Oil Tanks are Tested for Evidence of Leakage

Specialists and some oil companies have equipment to test buried tanks for leaks. Both simple pressure-testing and sophisticated electronic testing are used, mostly on commercial equipment, and more recently on residential tanks. Testing for water in the tank is simple and can be done by any service person using a simple chemical paste on a probe. A lot of water in the tank is a reason
to be pessimistic about its condition.

There are a number of tank testing methods currently in use, varying in risk to the tank, cost, invasiveness, length of time to complete, and some, requiring shutting down of the heating system during test period. See "How do you choose the right tank testing method?" Cynthia Johnson, Fuel Oil & Oil Heat Magazine, November 1995.

• Low-psi tank pressure-testing is used to test a tank for existing leaks.
• Soil testing looks for evidence of actual oil contamination in the soil. A proper soil test is based on having located the buried tank or the site where a tank was buried, and taking borings to a depth approximately just below the tank bottom.
• Electronic testing can also screen tanks for evidence of damage - usually this is used only on commercial jobs.
• Water testing in oil tanks can indicate the risk of in-tank corrosion and thus leakage - an easy first-pass which can be used at both above ground tanks and buried oil tanks
• Ground scanning radar or magnetic sensing is also used to locate buried steel tanks.

PRESSURE TESTING - Oil Tank Pressure Testing

Using this tank testing method the oil tank is sealed and pressurized to a low psi level, then carefully monitored for a pressure drop, perhaps for 24 hours. This method is comparatively quick to execute but I don't care for it.

• First, if there is a pressure drop, additional testing will be required to determine if there has been actual oil seepage into the soil. (A leak could have been a minor one at the tank top, for example.) The additional testing is pretty-much the same as my second method described below, so the consumer ends up paying for testing twice in this case.
• Second, even if there is not a pressure drop, I'm not sure that there hasn't been a tank leak in the past, perhaps fixed by a plumbing repair or other method.

Some home owners balk at this test, fearing that the pressure of the test procedure will "burst" an oil tank that is about to fail. I am doubtful that this is a legitimate concern. The pressure at which the tank is being tested is almost certainly a much lower psi than the pressure to which the tank is subjected while it is being filled by the oil delivery truck and driver.

SOIL TESTING - Soil Tests for evidence of tank leakage

I prefer this method, which may cost about the same as the first method.

Multiple soil borings are collected around the tank, at a depth just past the level of the tank bottom. The soil samples are tested for petroleum product contamination.

This is considered the definitive test for oil tank leakage, and if the tank has not leaked, it provides more reliable documentation of that fact. More time is needed to complete the test as there is a delay for the lab work.

Consider that if you opted for the tank pressure test described earlier, and if the test showed that the tank has leaked oil into its surrounding soil, some additional testing is going to be needed to confirm the extent of soil contamination. It seems to me it's better to test the soil in the first place, thus also covering not only current but past conditions.

Finally, if we are told that an oil tank has been "remove" or "abandoned" at a property, we expect to be given the documentation that outlines who did what when, and importantly, what steps were taken to assure that there was no oil leak that was simply left for the next owner to discover and clean-up. If adequate documentation is not provided, a soil test is certainly appropriate. One of my clients took this advice and discovered, and avoided having to pay for, a $60,000. site cleanup at the property he was buying.

TEST FOR WATER - Test oil tanks for presence of water

Buried tanks, such as heating oil tanks, should be tested for amount of water present in tank bottom, and water should be pumped out.

In fact, water can accumulate in indoor or outdoor above ground oil storage tanks too, either from exposure to varying temperatures (in-tank condensation) or from the occasional delivery of bad oil which contains excessive water content.

A neat way to look for a history of water in the heating oil storage tank is to check the oil filter canister itself. Many oil burners are protected by a heating oil filter installed either at the tank or at the oil burner. (Every heating boiler burning oil shouldhave one of these filters installed to protect the equipment.)

If the oil tank has a high level of water, especially if the oil lines run to the oil burner from the bottom of the oil tank, some of that water will have been making its way to the oil burner where, en route, it is (usually) trapped in the oil filter. If you open an oil filter container and see that its metal parts are rusted, or that there is a lot of rusty sludge in the bottom of the filter holding canister, the oil tank needs to be checked further for water

The oil service technician can check the level of water in an oil tank by putting some "oil finder paste" on the bottom of a stick or probe which is inserted into the tank and to its bottom. The paste changes color in the presence of water, showing, by the length of color change on the probe, the depth of water in the bottom of the tank. Obviously this trick is much easier if the tank is outside than indoors where a basement ceiling can make probing the oil tank difficult.

Ask your oil service company to perform this test.

While we've found them lasting longer, a common life expectancy of buried oil tanks is 10-15 years. We do not have the same data for gas tanks. Life may be similar.

If the tank is to remain in use, ask your fuel supplier about using an additive or other methods to help remove water. Warning: on some older oil tanks which had a lot of sludge in the tank, as the de-watering additive (such as "4-in-1-HOT (TM)") was added to the tank we found an increase in the debris making its way to the heating oil filter. You should inspect the filter cartridge for water and debris and have it changed more frequently until this question is closed. It's more trouble but the end result is a more reliable oil storage tank and heating system.

More Reading:

See WATER in OIL TANKS for added suggestions for finding and removing water from oil storage tanks.

A discussion of methods for finding evidence of previous or current buried tanks at properties is at BURIED TANKS, FIND

More detail about the chances that an oil tank is leaking or about to leak is at TANK FAILURE RATES.

More detail about the causes of oil tank leaks, both buried and above ground tanks, is at TANK FAILURE CAUSES.

Regulations governing tank leak reporting and tank abandonment as well as the registration of oil tanks at properties is at TANK REGULATIONS

More Information on Oil Storage Tanks, Underground and Above-Ground Oil Tank Leaks, Removal, Testing, and on Building Diagnostic Inspections and Repairs

• Oil Tanks - The Oil Storage Tank Information Website: Buried or Above Ground Oil Tank Inspection, Testing, Cleanup, Abandonment of Oil Tanks
• Abandon a Buried Oil Tank, How To - Abandoning Commercial Underground Tanks, Russ Brauksieck, ASHI Tech. Journal, Vol.3 No.1 Spring 1993, P. 40-41 [Reprint]
• Above Ground Oil Tanks: Visual Inspection of Oil Storage Tanks for evidence of leaks, damage, improper piping - photos and text
• Above Ground Oil Tanks Checklist, an Oil Company's advice
• Above Ground Tanks UL Standards, UL Tank Listing Standards, guidance for home owners, buyers, and inspectors
• Buried Oil Tanks - Finding How to Find Buried Oil Tanks and "Nearly Hidden" and Leaky Oil Tanks - photos and text.
• Buried Fuel tank - Advice - Buried FUEL Tank - GAS or OIL advice for home buyers, inspection report language
• Environmental Issues & Regulations for Oil Tanks, Registration, Abandonment, Leak Reporting
• Home Inspection Report Language Library: Buried Oil Tanks, Basic home buyer advice - home inspection report language suggestions
• Home Inspection Report Language Library: Visible Defects in Oil Tank Installations, Tanks, and Heating Oil Piping
• Home Inspection Report Language Library: Gas Fuel Piping or Tank Faults Basic advice - home inspection report language suggestions
• Home Inspection Report Language Library: Oil Tanks text file list © Oil and Other Storage Tank Leaks, Testing, Abandonment, Inspection - UST home inspection report language files - Reference List
• Indoor Environment Website Indoor Building Environmental Hazard Detection, Testing, Repair, & Prevention - Main Web Page
• Leaky Heating Oil Tanks - Advice for Home Owners or Buyers: caused of leaks in oil tanks, oil tank testing alternatives, what to do about leaky tanks: D.J. Friedman, ASHI Tech. Journal, Vol.2 No.1, Winter, 1992 p. 42-43 Illus
• Leak or Failure Rates for Home Heating Oil Tanks
• Legal Issues Regarding Buried Oil Storage Tanks K.S. Rea, Attorney, summary from ASHI Chapter Seminar.
• Primer on Petroleum Bulk Storage Tanks & Petroleum Contamination of Property Paul H. Ciminello, ASHI Tech. Journal, Vol.3 No.1 Spring 1993, p 35-39
• Petroleum Bulk Storage J. Sibblies, NY State DEC, Advice to Home Owners and Home Inspectors about Oil Storage Tanks - summary from ASHI Chapter Seminar.
• Septic Tank inspection, testing, diagnosis, repair
• TANK FAILURE CAUSES - Oil Tank Failure Causes - oil tank leaks are caused by corrosion, damage, soil conditions, other factors
• TANK TESTING - How Oil Tanks are Tested for Evidence Leaks, of Current or Previous Oil Spills
• TANK FAILURE RATES - Oil Tank Failure Rates - Oil Tank Leak Probability as a Function of Tank Age, Location, Condition, Soil Conditions and Other Factors
• Web Link Exchange: Contact Us to list your website or contact information for oil tank testing, tank corrosion research, oil industry experts

The Buried and Above Ground Oil Storage Tank Website inspection, testing, replacement of leaky or leak-risk heating oil storage tanks

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