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Water in Oil Storage Tanks
An owner's guide to preventing, or measuring & removing oil tank water contamination

  • POST a QUESTION or COMMENT about how water gets into oil storage tanks and what problems it causes in oil fired heating equipment

Water accumulation in an oil tank from flooding or from leaks into the oil storage tank:

Why is water in an oil tank a problem? How water gets into an oil storage tank - assessing the level of water in an oil tank: water finder paste, instruments, visual inspection .

This article series explains the problems caused by water accumulation in oil tanks, how water gets into the oil tank, how to measure water in the oil tank, how to remove water from oil storage tanks regardless of whether the oil tank is indoors, outdoors above ground, or buried, and how to prevent water from getting into an oil storage tank.

We explain how to test for or visually check for water in a buried or above-ground oil storage tank, and how to get water out of an oil tank. Extensive free un-biased oil storage tank inspection and testing advice for property buyers and owners is provided at this website.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Testing for and Removing Water Contamination from Oil Storage Tanks

What problems are caused by the presence of water in heating oil or heating oil tanks?

Photograph of an oil tank filler flush with the ground.According to R.W. Beckett, a major manufacturer of heating oil burners and related equipment, water in the heating oil tank or piping system causes the following "nuisance service problems" problems [edited, paraphrased, amplified - Ed.]:

Testing an oil tank for for water contamination in an oil tank (above ground oil tanks whether inside or outdoors, or buried oil tanks) is simple and can be done by any service person or even a homeowner.

Oil Tank testing methods for oil leaks vary in risk to the tank, cost, invasiveness, length of time to complete, and more.

Since water in a heating oil tank can lead to loss of heat and related building damage we want to know if in-tank water is a problem at a given property. There are several steps and test methods for finding water in an oil tank and for determining how much of a problem it is.

How Does Water Get Inside a Buried Heating Oil Storage Tank

Details about how water leaks into or condenses in buried oil tanks are at BURIED OIL TANK WATER ENTRY. Excerpts are below.

How Does Water Enter an Above-Ground Oil Storage Tank

Details about how water leaks into or condenses in above-ground oil tanks are at  ABOVE GROUND OIL TANK WATER ENTRY. Excerpts are below.

Sources of water entry into above ground oil storage tanks are similar to the underground oil tank water leak sources listed just above.[Paraphrased, edited, and expanded from R.W. Beckett]:


Steps to Reduce the Chances of Water Entering an Outdoor Above-Ground Oil Storage Tank

Details about how we keep water out of oil storage tanks are found at OIL TANK WATER PREVENTION. Excerpts are below.

[Paraphrased, edited, and expanded from R.W. Beckett and other sources]:

How to Measure the Level of Water Contamination in an Oil Tank

Oil storage tanks would ideally be tested for water accumulation at every oil delivery, but as that simply is not going to happen, you should ask your oil company to assess the amount of water in the oil tank at least once a year by using one of the methods discussed

at OIL TANK WATER DETECTION where we provide details about measuring the level of water contamination in heating oil tanks. Excerpts are below.

A simple method that can be used on oil storage tanks whose fill pipe is located directly above the tank is to insert a dipstick into the oil tank after coating the dipstick end with a water-finding paste. (photo at left).

A similar test for oil tanks whose piping does not permit use of a dipstick makes use of a string and weight and water finding paste.

Where to Buy Oil Tank Water Finding Paste or Water Indicating Pastes

Other Methods for Detecting Water Contamination in a Heating Oil Tank

Ask your oil company service technician to check the oil filter for evidence of water or rust, or if you've had heat outages ask if water in the oil could be a contributor or cause.

See OIL TANK WATER DETECTION for details about methods of testing for water in oil storage tanks.

Foam Formation in Wet Heating Oil

Reader Question: foam formed when new oil was put into tank that caused it to indicate full and stop pumping

14 Feb 2015 Anonymous said:

I asked the oil man to fill my tank that read 1/8 tank. When he came he pumped 110 gal and it indicated full to delivery man. The guage read 1/2. They told me that foam formed when new oil was put into tank that caused it to indicate full and stop pumping. I've never heard of such a thing! Any comment?

Reply:

Anon:

What you describe is not something I've come across but it has been described as an effect that can occur if there is water contamination in the oil storage tank; during delivery the incoming oil, delivered fast and under pressure, can stir up water and form foam - this can also clog up the heating oil piping, filter, burner, and lead to loss of heat.

I'd ask the oil company to check oil tank water level, remove excess water, and go from there.

I'd also check - if you can - about just what was being delivered to you - if your oil tank didn't have much water in it before then water could have come in a bad delivery. I've seen this happen if the oil truck is filled from a depot tank that is low on oil, has water in that tank bottom (which is normal) and is itself stirred by a depot delivery while the oil truck is filling.

Experts have written about this, describing the formation of a water-oil emulsion and problems that it causes in heating oil production and usage; see in parcitular Maslennikov (1969)

This Q&A was originally published at OIL TANK GAUGES

How to Remove Unwanted Water from an Oil Tank

Details on how we get rid of water contamination in an oil tank are now at OIL TANK WATER REMOVAL

 

 




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-02-17 - by (mod) -

Interesting idea, John. I suspect that the sludge and debris common in oil heat systems risks a clear sediment bowl becoming obscured rather quickly; you could try having a transparent heating oil filter canister bottom made to see if that idea would work.

On 2020-02-17 by JohnfCockerill@yahoo.com

What about adding a visual device like a sediment bowl to watch the oil coming through to the burner. It would seem that it would have to be larger than those used on tractors and cars years ago.

On 2018-06-22 by (mod) -

Mike

If you are really lucky water has leaked INTO the tank from above but the tank itself is not leaking. There's a fair chance that that's the case, based on your description.

In that case you can proceed to do what should have been done in 1999 - abandon the tank properly by having it emptied, tested, and filled - often using sand.

But if the tank has leaked the leak will need to be cleaned-up. And pretending it never happened is bad

1. because your tank is contaminating the environment, aquifer, etc.

2. it's illegal in most countries and cities

3. the future sale of your home could hit an ugly snag right at a bad time -

If it were my tank I'd have it emptied then tested for leaks. An alternative is to have a oil tank leak test done by testing the soil at the level of the bottom of the tank.

If all is OK then proceed with the abandonment.

See OIL TANK ABANDONING PROCEDURE https://inspectapedia.com/oiltanks/Oil_Tank_Abandonment_Procedure.php

On 2018-06-22 by Mike Landis

I have a 550 gal underground tank last used in 1999. When it was no longer used it was left with about 1/2" oil in tank. Out of curiosity I checked it today and the dipstick was wet about 2 feet which means to me there is about 24" water in there.
What should I do?

On 2018-01-07 by (mod) -

Jay

Some oil tank cleaning companies can remove sludge, often using a combination of an additive to break down the sludge so it can be pumped, and a pony pump to siphon out sludge and water from the tank. It won't remove all of the debris but you can sometimes get quite a bit out.

Water must be removed and is easier to pump out.

I might go to

- a larger diameter oil line tank to burner,

- double capacity oil filters

or
change oil piping to take oil out at the top of the tank, with a pickup line higher off the tank bottom

On 2018-01-04 by JayJ

My 22-year-old oil furnace NEVER gave us any trouble until about 14 months ago. (Here in suburban Maryland, we use approx 500 gals per year; my tank is located in the basement.)

But in Nov 2016 I let the tank get too empty, and got a fill of 240 gals on a 275-gal tank. A few days later, the furnace burner locked up from water and/or sludge. In the resulting service calls over the next 2 months, we got 3 nozzle replacements, a pump replacement, filter replacement with a fancier model. This past fall it ran fine from mid-October to last week,

but on Dec 28 I got a fillup of 127 gals, then on Dec 30 the system locked up again. The same service guy arrived today, replaced the nozzle, pump, and filter cartridge again, and showed me the amazing amount of dark brown sediment around the nozzle. The new fancy filter was a complete failure, as far as I can see.

For the moment we are warm again, but I don't have a good feeling about this.

I guess my questions are:

(1) is there a way to suck out water/sludge/sediment from the bottom of a tank without emptying it?

(2) my tank's fuel outlet is at the very bottom of the tank; it seems smarter to have it a few inches above the bottom. Is there a way to make that change without emptying the tank?

(3) The Maryland Dept. of Environment says that aboveground tanks last 20 to 25 years and eventually corrode from the inside, which is scary

; I don't like the sound of an oil leak in my basement. All in all, I'm strongly considering a conversion to propane in 2018. What advice do you have? Thanks.

On 2016-12-13 by Glen

How to remove water from the oil tank with chemicals.

On 2016-11-18 by James

We have some water in our kerosene jug...how do we remove it so we can use our kerosene heater. Thanks

On 2016-11-11 by Charlotte

How do I remove water from my tank with chemicals

On 2015-11-17 by (mod) -

Anon:

We don't need a new oil tank solely because water got into the old one. We need a new oil tank if the existing one is perforated, leaking, or has rusted (from inside in this case) so much that the remaining tank wall thickness is too thin, risking a costly oil spill or leak.

For an old but in-good-condition oil tank the water is simply removed by a service company.

IF you do need a new oil tank then the oil from the old one can be pumped out and used in the new one.

On 2015-11-17 by Anonymous

I am having a new tank because water is getting into my old one, will i be able to use the oil that is in the old one

On 2015-10-20 by (mod) -

Wow. With an oil tank filled, presumably you got an oil delivery not a water delivery, I have to figure that your oil lines are taking fuel from or close to the tank bottom so picked up the water.
An underground tank would typically be piped from its top with the supply and return line ending a few inches from the tank bottom. I wonder if your lines are too low in the tank.

You can calculate the possibility of your question about the Tigerloop: look at the firing rate of the nozzle in GPH, estimate how many hours the burner ran, and you'll know what volume of oil would have been needed for the initial 30 minutes.

On a typical residential system that would certainly be less than a gallon (few residential systems fire at 2 gph

). So yeah your piping and filter and tigerloop could have held enough oil to run 30 minutes.

If this had happened right after an oil delivery, then It would have been possible that your oil delivery was contaminated, OR that the delivery stirred up water in the tank; If the latter happened, then the system might run ok at first (the water is mixed up with the oii but after a few hours the water settles to the bottom and is then sent out to the oil burner as mostly-water.

On 2015-10-19 by Rey Barry

I had the oil tank filled with 7xx gallons in August. The first oil burner run of the season was last night. It ran flawlessly for 30 minutes, warming the water through the house in 3 zones. When I woke the next morning, the burner had quit and would not restart. The pump was bringing in water, only water.

I checked the 1000-gal underground tank (Sar-Gel) and there was 1.5 inches of water, around 10 gallons! I'm familiar with water-in-tank conditions, but what accounts for flawless running last night? Can a 2A-700A filter feeding a Tigerloop hold enough oil to run the burner for a half hour before the water took over?

Question: discovered a lot of water in the tank

(Jan 24, 2014) D said:
We had a top up of heating oil and 2 to3 days later our boiler and oil fire went out . Our boiler man discovered a lot of water in the tank. Oil company dont want to know alot of damage to boiler and still cant get fire going

Reply:

D.

The article above describes how water is removed from the oil tank. If water has not been removed then it's likely that trying to start the boiler is futile because it keeps drawing more water into the system.

If the oil lines are taken off of the tank bottom it will not be possible to avoid water in the fuel without either having it all pumped out or by re-piping the oil lines off of the tank top (and keeping the oil line pick-up height inside the tank above the bottom and above any water.

There are commercial oil filter systems that can help trap and remove water as well, but for a residential installation this ought not be necessary.

If you find that the water in your oil tank got there by a bad oil delivery that contained a high percentage of water then you got a bad oil delivery - something to discuss with your oil company.

Keep us posted.

Question: My fuel tank went bad,in pumping out the 200 gal. of fuel I ended up with contaminants in the fuel

(Aug 16, 2014) bob said:
My fuel tank went bad,in pumping out the 200 gal. of fuel I ended up with contaminants in the fuel. Is there a way to "clean" the fuel so it can be used in the new tank? Thanks, hrcicio@yahoo.com

Reply:

Bob,

If the contaminants are sludge and debris you can install a double capacity oil filter and change the cartridge frequently until things settle down.

If the contaminants are water, there are water suspension products that remove small amounts of water; or if there is a lot of water your oil company can pump it out of the new tank (water will be at the tank bottom).

On 2012-01-03 by Art

Showing results for I live in northern Minnesota and had 5 below this morning. My heat quit and I put a hair dry on the line the heat started up but I do belive ice is in the tank how can I remove it?
Search instead for I live in norther Minnesota and had 5 below this morning. My heat quit and I put a hair dry on the line the heat started up but I do belive ice is in the tank how can I remove it?

On 2011-11-05 by Jason

I have an oil tank in ground that I pumped to my out of ground tanks. Initially we pumped a champagne color out then it turned red. Is this a sign of water in my tank or is it two different oils, dyed and undyed?

On 2011-10-03 - by (mod) -

Susan I can't even guess at a problem diagnosis for your heating system with just the information in your question. Certainly if the problem is water in the heating oil supply, that can result in improper operation and nozzle clogging at the oil burner. Your heating service tech can confirm whether or not water in the heating oil is a problem by inspecting the oil filter canister base for water, rust, sludge that may be passing into the oil burner itself. Also be sure the filter screen INSIDE the oil burner fuel unit (oil pump) has been changed.

If there is water and crud in the oil tank it'll need to be pumped out.

On 2011-10-02 by Susan

our oil furnance won't stay lite .we have replaced every thing that we can on the furnance do you think it's the fuel oil ?

On 2011-08-28 by Andrew

Helpfull Info Thanks :)

On 2011-07-14 by Joanie

Thanks this site is very helpful.

On 2011-06-03 - by (mod) -

Thank you for the nice comment, Biffo. We are dedicated to making our information as accurate, complete, useful, and unbiased as possible: we very much welcome critique, questions, or content suggestions for our web articles.


On 2011-06-03 by Biffo

Some really good tips,never realised what went on in my oil tank until now especially methods to extract water from the tank,excellent web site.



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Continue reading at ABOVE GROUND OIL TANK WATER ENTRY or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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Aboveground Oil Storage Tank Water Contamination Articles

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OIL TANK WATER CONTAMINATION at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING OIL, OIL BURNERS, OIL FIRED HEATERS, OIL TANKS

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