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Understanding the Dangers: Why Simply Pumping Water Out of an Underground Oil Tank Won’t Solve the Problem

Fuel Tank

Why You Can’t Just Pump Water Out Of An Underground Oil Tank

“Hello, GreenTrax? I’m calling to get my oil tank pumped out. I don’t want to remove it. Just pump it out.”

That’s a typical phone call we get at GreenTrax HQ. Or here’s a similar one: “I have water in my tank so I just want the water pumped out and the tank filled with new oil.”

Let’s discuss why that’s a bad idea to try to just have your tank pumped. 

First, we will assume we are talking about a UST, or buried heating oil tank (or underground fuel tank). 

If you have water in your tank, that is bad. Period. End of story. But we won’t just stop there. 

Let’s tell the rest of the story, as there are several ways water can get into the UST:

  1. If the oil fill pipe is very low to the ground so that it is flush with the grass – or even slightly below the grass – and someone left the cap off during a heavy rain, water can get in that way.
  2. There could be holes or breaks in the tank oil fill and or air vent pipes and water gets in.
  3. You could have holes in the top of the tank itself and rainwater soaking into the ground leaks into the tank.
  4. Finally, the most common reason people have water in their tank: they have holes in the bottom, sides, or ends of the tank and groundwater goes in & out of the tank (along with oil).

Items #2 through #4 above are indicative of the tank leaking. Item #1 contributes to a tank leaking. Let’s discuss each of these. 

Why It’s A Problem When Your Underground Oil Tank Fill Pipe Is Too Low

So, there are always two pipes sticking out of the ground for a buried oil tank. One is for oil to go 

into, and the other is for air to come out and that pipe also functions as a whistle to let the delivery company know when the tank is full. 

If either or both of those pipes are low enough to the ground that rainwater can collect and get into the tank, that is bad. 

Those pipes should be at least 12 inches – or ideally 24 inches – above the ground. What you might find even more surprising is that the water didn’t just start going into the tank, it’s been that way for years and decades. 

So, the water’s been likely building up in the bottom of the tank over years. Finally, it gets high enough that the oil suction supply line takes it to the furnace or boiler and your heat shuts off. 

Typically the water will have to get to three or four inches in the bottom of the tank before that happens. It doesn’t take that long for problems to start, though. Any amount of water in the tank will contribute to faster corrosion. 

Now, you may be thinking, “Ok, we will just have the pipes raised then, right?”

Wrong! Bad idea. I just told you it’s been that way for a long time, so the damage has been done. 

Besides that, the tank is past its useful life anyway, so it’s not worth fixing any underground residential tank because 99% of them are 30, 40 or 50+ years old. 

They have to be removed and replaced. 

How Cracks In Your Oil Tank Lead To Leaks

The second reason about how water gets into your tank are actual holes, cracks or breaks in these pipes we just discussed. 

This happens either from age, deterioration, or someone hitting the pipes. The important thing to know here is that the steel pipes are Sch40, meaning the pipes themselves are actually thicker steel than what the tank is made from. 

So if the thicker steel has rusted through, what do you think the thinner tank steel looks like? 

Yes, you guessed it. Not good. 

If someone has struck and broken one of these pipes with a lawnmower, machine, or vehicle it could have broken the pipe off at the tank itself. It could also have damaged the threaded connection at the tank, which means the tank again is no longer good and needs to be removed.

What does that mean for you? It’s time to remove or properly abandon the tank in place. 

How Rainwater Can Seep Into Your Underground Oil Tank

If there’s water in the tank, you may have holes in the top of the tank that are allowing rainwater to seep in. 

This usually happens from the tank sitting in an area where water ponds up on the surface of the yard. It could be that it gets more water absorption in the ground in that area, or perhaps you have a downspout dumping out right over top of the tank area. 

This leads to the top of the steel tank to get holes in it and take on water. This also means when the tank is filled with oil, the oil likely comes out through those holes as well. This creates contaminated soil on top and around the sides of the tank. 

The Most Common Reason Your Underground Oil Tank Has Water In It

The most common reason a person has water in their buried oil tank is the tank has holes in the bottom or ends of the tank. 

These holes allow groundwater to enter the tank, while at the same time letting oil out of the tank. 

Despite popular belief, you will not realize this. 99.9% of the time it happens so slowly you cannot track it by the oil usage, by sticking the tank, or by checking with the oil company. 

This also means the water level in the tank will change. Maybe one day we check the tank and it has 3 inches of water in it, but then when we arrive to remove the tank it has no water in it. 

What To Do If You Find Out Your UST Has Water In It

Bottom line is if you have water in your tank at all, don’t waste time and money trying to get it pumped out to keep using the buried tank. 

The water will return and it will happen again. 

GreenTrax will install a new aboveground tank for you quickly so you are back up and running – often in less than a day! Then we will remove the tank properly and take care of the entire process for you. 

One last thing – this doesn’t only affect underground oil tanks. You might also have water in your aboveground tank Located outside or in the basement. 

This is not as common but does happen occasionally. Depending on the age of the tank, this may be able to be addressed if we know how the water got in, or if the tank is over 20 years old. 

Then again if the tank is over 20 years old, the tank needs to be removed and replaced with a new aboveground tank. 

Call us at (410) 439-1085 for questions or to get a price on a tank removal and/d or replacement, or send us a message here.

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