Blockage at Septic Tank

We live on a rural property in Canada. Our septic tank is located about 6 ft from the house, and about 10 ft from the toilet. Our toilet is a conventional 3-gal American Standard model, approximately 10 years old.

Periodically, toilet paper builds up at the inlet to the septic tank, causing a blockage. (This most often happens with a house full of guests!) Plunging the toilet has no effect. The only way to clear the blockage is to open the septic tank and clear the blockage at the inlet. I have made a clean-out tool out of copper pipe which works well. Usually, the blockages are easy to clear.

The drain pipe does not appear to have any obstructions and I haven't found any evidence of root growth. Both house and tank are about 30 yrs old, and I am wondering if settling has resulted in a small uphill slope to the drain pipe which slows the flushed material and causes a blockage when there is too much paper, etc.

Would a Gerber pressure-assisted toilet move the flushed material down the drain pipe faster, and thereby help to keep the pipe clear? Is there something else I should consider? I would like to avoid having to dig up the septic tank if at all possible.

Thanks,

Reluctant Septic Tank Technician

Pressure assisted toilets are not a miracle cure for a mechanical defect in a line. I recall a job I camera inspected in a supermarket where we found a belly that had an elbow in it. The line was clear except the belly and when the pressure assisted toilet was flushed the lav which tied in just before the belly would erupt with a geyser...

Your results may vary.

Its more than likely the toilet paper. All this new and improved stronger paper is horrible stuff. Its like flushing paper towels down the drain. An old timer taught me a way to see if the paper is safe for a septic system. You get an empty jar that has a lid, fill it half way with water and toss in one square of TP and pt the lid on and give it a shake for 20 seconds. If the paper clumps up or is in piece its no good, if it breaks up into 1000's of pieces its a good safe TP.

Also, 30 years ago toilets and waste systems were designed to use more water to efficiently move the waste out of the house. Now w/ 1.6 gpf toilets, the water doesn't take the paper all the way out of the house and allows for the next load with lots of paper to add to the remainder of the prior flush.

You can change toilet paper and things will get better, but it won't fix the secretly disposed of used tampon that always makes it's way into the sewer even though none of the women in the house will admit to doing it. Those things can clog up a perfectly good sewer system all on their own.

Thanks for the great advice! We will try changing toilet paper. We are currently using a medium-grade embossed 2-ply paper. I have found some favourable reviews of Scott one-ply paper so we will try this brand first. Whichever brand we settle on (?!), I will post the results here.

Thanks again!

Reluctant Septic Tank Technician

SepticTankTech said:

Whichever brand we settle on (?!), I will post the results here.

Click to expand...

Are you thinking what I think you're thinking¿

Another important factor is the slope of the pipe going to the septic tank. In PA the code required that the last 10' of a pipe prior to entering the tank be sloped no more than 1/2" per foot. This keeps the velocity down and reduces blockages. In addition, any horizontal pipe needs to be carefully sloped so that the solids are not left behind as the water moves quicker when the solids start to drag on the invert of the pipe.

I am going to bet the pipe has no fall or is pitched back...taking a shower and doing laundry would / should push the paper into the tank...unless the tank needs to be pumped...

Had the same problem a few years ago. Turned out there was a length of old orangeburg pipe which had not only flattened out a bit, but developed a dip about 3 feet from the septic tank. Replaced it with PVC, never a problem since.

No more than a 1/2" per foot? The whole line should be no more than a 1/4" per foot, and thats for 3" pipe and smaller. larger pipe up to 8" should be no more than 1/8" per foot.here this is from the Illinois code book.

Yes 1/4" per foot, my typo again on this stupid notebook with a small keypad. I hate this thing, very unstable and I make more typos than I care to..

I am quoting the sewage book, not the plumbing code. The minimum is 1/8" per foot but the max is 1/4 only during the last 10' prior to entering the tank.

The plumbing code ends 30" outside of the foundation.

In addition, you are limited to 45 deg bends between the foundation and tank.


As far as pipe size. =<1000 gpd = 3" line, >1000 gpd = 6" min UNless specified differently by the plumbing code inside the house.

so if you have a 4" building DWV pipe leaving the foundation (due to Dfu's)then you must not be any less than 4".