Septic test failed

So, I ran 240 gallons into the septic tank at rate of 6 gallons per minute for 40 minutes. Before starting test effluent was 88 inches from top of pvc riser, upon completion of test effluent was 77 inches from top of riser. I recommend pumping tank, and having it inspected to determine if concrete tank installed in 90 was leaking or drain field is backing up. House has been unused for a few years what do you think the problem is?


Could be many things.

Report what you see and refer it out to a septic installer.


Well, if it was leaking it would not be rising up the riser.

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I was curious if it was leaking before the test, as the house had sat unused, and was rising to the level of the outlet.

I have not been trained on septic inspections so I am curious. With the parameters given in your post, what are the expected measurements for a properly performing system?

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I would expect the effluent to stay the same level throughout out test, and at completion of test not rise. Which would indicate water was flowing out of drain field into tank.

How many tanks/compartments are in this system and which one do you take measurements at? My septic system has 3 compartments if I remember correctly. The first one should be the only one with solids and the last one has the pump to the mound drain field.

If you have access to all three I would keep an eye them all, I manly pay attention to the outlet, as I think you are more likely to identify a problem there. The tank yesterday had one access in the center.

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So is it possible your testing brought the level up to the point pumping would begin and then it stayed static after that point? As Jeff stated above, the tank was low at the start point.

What Are The Different Types of Septic Systems, Type 1, Type 2 and Type 3  System


It is possible it’s evaporation , but I would expect the majority of evaporation would condense on top of tank. The diagram shown above is not what was inspected, this was a concrete tank with baffles.

Wouldn’t that be just the opposite…more effluent? Like [these ?] risers (Polylok 24'' x 3'' Septic Tank Riser - 3008-RP - Septic Tank Risers and Lids)

This is less effluent…88 inches from top of pvc riser.

And, this is more effluent…77 inches from top of riser.

And also yes I think it’s complete possible I raised the level to the outlet level. Bit being on a well wasn’t willing to go farther.

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I understand that. But the principle is the same I believe. Just trying to understand why a rise in effluent would indicate a failed test and what the expectation should be in case I ever add this service to my company. Do you verify that the pump runs and how often during the test or did this system not have a pump?


It was a gravity system, I set the flow rate to just above where the well would not cycle on and off. I use a water meter to verify flow rate, and gallons used. I run it from a hose bib to an outside clean out.

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Since the system has sat unused for a few years, it would seem like you would need to know the size of the tank to determine if any of the water you added made it out of the tank. That or you have to run so much water that it is obvious it is making it out, or not making it out.

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How thick was the scum layer? The solids layer? Did it have a filter? Was it evaluated?

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Scum layer was 4.5 inches, I did not measure the sludge.

And no filter.