Septic Tank Question

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I purchased a house with a 15 year old 1500 gallon concrete septic tank. The home inspector found that the level of fluid in the tank was 6 inches lower than the outlet pipe, suggesting a leak in the tank, since the tank had not been pumped in 2-3 years. Only 2 adults and one child live in the house with a septic sytem capacity built for this 4 bedroom house. Baffles were normal. The leech field was in excellent condition.
A contractor for the seller pumped out the tank and inspected it revealing some cracking next to the gasket joining the upper and lower halves of the tank. He repaired this with hydraulic cement, but felt that the crack did not seem significant. He also said that there was very little mortar left around the collar of either the outlet or inlet pipe (can't remember), and also repaired that with hydraulic cement.
My question: Do the findings of the contractor reasonably match the severity of the problem (water level 6" below outlet pipe)? In other words, is the low level of water usually in your experiences due to a HUGE problem, or sometimes just due to small fixable cracks, like I described above?
THANKS!
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I don't know a whole lot, but I'll add my 2 cents. Without being there, was the house sitting empty for a period of time? If so, a low level maybe normal. If people lived in the house when the water level was checked, where did all the water go? Is it wet aroung the tank? If it isn't wet around the tank, and more than one person lived there, there may be another escape route for the water. Look around, check for wet spots in and around the yard/septic system. You can also get a dye and put it down the drains, then run lots of water. The dye will appear somewhere. Then you can decide what problems, if any, you have.
Your local health department may give you the dye, or come out and check it out at now cost to you. But, you may be in for major repair bill if they find something.
Good Luck,
Hank
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Hustlin' Hank wrote:

Inspected and repaired, probably OK. I had a similar minor repair on mine. Concern would be solids reaching leach field clogging it up and you say yours is OK. With change in house population field could get wet if there are a lot more people in house. In our area, new construction requires a 2nd leach field for backup.
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MC wrote:

We had a septic tank leak that came to surface when I was a kid. We had the biggest, plumpest raspberries in the neighborhood.
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wrote:

Usually the problem is a septic tank that is too full, not full enough. For arguments sake, let's say there is some opening in the tank that is allowing some of the water to leak out. The water has to go into the ground anyway, whether via the leach field or from the tank leak. In years gone by, that was with a cesspool, which was essentially a tank with no bottom.
The only issues I can see would be if the septic tank location is less than the code distance from a well. Or if water is coming up at the surface near the tank, etc.
Otherwise. I wouldn't worry about it.
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Thanks for the replies.
The house has been occupied continuously.
Could you guys please clarify something for me. If the tank is 1500 gallons, shouldn't the water level in the tank ALWAYS be at the level of the outlet pipe (assuming that at least 1500 gallons of water has been flushed down the drains) if there is no leak?
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wrote Re Re: Septic Tank Question:

You probably have a small crack at around 6" below the out-flow pipe in the 2nd chamber. It's probably very small, since a large crack would be obvious. Being small, the only thing that will leak out is liquid, not solids. The water that leaks out will be absorbed in the soil, just like from the leach lines.
One thing you can do is fill the tank, and time how long it takes for the level to drop 6" without any water going into the tank. Obviously you will have to do this when no one in the house is using water. Knowing the dimensions of the tank and the time it takes for the level to drop, you can calculate the leak rate. I'll bet it's very small.
You could probably find the leak by digging around the sides of the tank to a depth of 8" below the tank top (bottom of the lid).
I wouldn't worry about it unless you see water coming to the surface or causing a muddy condition.
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Check to see if there are two tanks. My in laws house was like this with one for gray water and the other a black water tank. The black water tank was almost completely dry when it was inspected. Gray water was used on the garden, lawn and fed into a small pond full of aquatic plants. The septic tanks had never been pumped in 30 years and still didnt need it. My father in law was very particular about what went down the drain, no grease, no garbage diposal, no caustic chemicals. He was green before it was popular. He just called it saving money.
Jimmie
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thanks
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I can remember reading many years ago, that some septic systems utilized a syphon system in the second tank. The purpose of the syphon was to hold the liquid until the second tank was full then the syphon would automatically activate and empty the tank into the leach field. Checking the tank after the syphon had emptied it would look like a tank that was low due to a leak. I don't know when they stopped using syphons, if they ever did, in some areas. I have never seen one in person, despite using septic tanks for the last 55 years.
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A quick Google check shows that septic tank syphons are still in use in many areas.
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Would everyone agree that maybe my best bet would be to wait until the tank fills with 1500 gallons of water over 3 weeks following the pumping/inspection of the tank in order to see if the water level reaches the pipe, as it should if the leak has been fixed?
Can anyone think of anything else bad that might cause the water level to be low that could be missed on an internal inspection of the tank? Im assuming that the person who inspected it is honest and there were no other cracks. Can cracks in a concrete tank be accidentally missed with internal inspection? I'm basically trying to decide if I should hire someone else to inspect it.
Points about this not mattering as long as the septic tank is not near well water (no well water, city water) are well taken. I also realize that an overflowing tank is more of a problem, but the tank is right next to the house and I don't want this stuff leeching into the basement, etc.
Thanks
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Yes; a leak between the house and the tank causing the liquid never to reach the tank.
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I guess. But that would have to be a huge leak to prevent the accumulation of 1500 gallons of water in the tank over a 2-3 year period. Plus we flushed a toilet and saw all of the water come from the pipe into the tank.
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MC wrote:

How do you know it was "all"??? :) That would take a volumetric measurement on both sides which undoubtedly wasn't done. Not that I would suspect too much, just a point that you can't draw excessive conclusions from simple observations.
As for the overall situation --
First is the question of the tank design, etc., ... was/is there a siphon that could account for the permanent level?
Were any cracks/potential leaks that were fixed/repaired below the level that could account for it? I've not read the whole thread by any stretch but did see indication that what appeared to be most problem(s) may have been at the level of the outlet which wouldn't have explained the low level anyway. If misread that or that's wrong, ignore...
Is the house presently occupied? If so, it shouldn't take any time at all for the level to reach the outlet level (in overall terms); normal household activities will put quite a level of water down the drain in a day or so unless there's some very stringent usage restrictions being observed by the occupants. If so, observing the level should lead to fairly quick conclusion as to whether there's an escape path somewhere or not.
If it's unoccupied, and the tank is still open, I'd just fill it up w/ hose and other running water until it is at the outlet then watch to see if it goes down from there for a period.
As for leak in exit line from house, how deep is that line and what's it made of? Unless it's quite deep it shouldn't take much investigation to discover (particularly since you say it's short) whether there's waterlogged soil in the area -- even a probe rod should tell you the answer of whether there's saturated soil or not close by.
That last holds for areas around the tank as well--if you can probe deeply somewhere indicating soft ground, that would be telling of leaking--of course if it's in area of repair above, that could/would likely be old, not new.
All in all, if the house has been occupied and used in normal fashion w/ reasonable number of occupants and there are no visible indications I'd tend to think it's not a major problem.
You might want to write in a clause in any contract that owing to the circumstances any subsequent problems uncovered or becoming apparent within oh, say one year, are to be covered 50:50 or something similar by you and seller.
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dpb wrote:

The only possibility that makes sense and conforms with the existing evidence is that someone is stealing the fluids from the tank. Maybe at night.
Be vigilant and maybe the answer will be discovered.
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The thief will be in deep shit when he gets caught.
Hank <~~~~wants to know how much turds are selling for on the street
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HeyBub wrote:

Just put it in barrels out front with a price tag on them and somebody will steal them.
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Yes, it has to be filled up after being pumped out in order to determine if there is a leak. I am assuming you had it pumped dry. In reality, the people who lived there before may have put another tank elsewhere, or ran a line around the tank, or any number of possibilities. Just because it would be illegal, doesn't mean it can't be done.
Once the tank fills with water, then any leaks should show by water coming to the surface, if installed correctly. The dye will tell you that along with visual inspection around the tank.
Also, run your water for a few minutes and listen to see if water is flowing into the tank. Like I said earlier, it may be directed to another place.
Did you call the Health department to see if they would check it? Didn't think so. :-)
Hank
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Yeah, they pumped it dry to inspect it. The water is flowing into the tank--we flushed a toilet and watched; so no extra lines or anything like that.
The issue I have with using the dye is that there is no wetness around the tank to begin with. If there's a leak, it's small/slow and it's not showing up at the surface. Would dye still be helpful in that case?
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