It's been 4 months since we moved in to the newly constructed house and the septic tank is quite large (like 10 feet length, 6 feet depth and 8 feet width).

Water seems to be backing up in the toilet bowl and takes a good amount of time to drain at ground floor, and the toilet makes some noise as well.

Please look at the videos I have linked here.

Toilet 1 with Lower water level

Toilet 1 with Higher water level

Toilet 2 with lower water level

Toilet 2 with Higher water level


  • The Septic tank has open bottom with the ground
  • Toilet 2 in the video is actually on top of the septic tank
  • Toilet 1 is 50 feet away from the tank
  • Toilet 2 drains bit faster than Toilet 1
  • Once a month, I drop Bio-Septic cleaning liquids into the toilet
  • I checked out the air vent and it's fine.


My building engineer told me that there's no way the septic tank can fill this fast.

EDIT: I opened some couple of caps at Septic line's elbow and water started overflowing.

enter image description here

These elbows are like 2 feet high from ground which I'm really surprised how come water went up to that level.

In order for water to come up to this level ,Septic tank should get filled up completely then water will go up in the septic line.

I had to use 5000L septic tank cleaning truck twice to pump out all the septic sewage.

I'm worried whether the roof of toilet might cave in ?


How many times in a year I should be pumping out the septic tank ?

Any affordable solution is appreciated.

  • 1
    Toilets are usually sealed to the pipe with a wax ring, so your mason might be wrong. If the toilet is leaking there, it might also cause problems with the venting. Might just have a clog in the drain pipe for that toilet.
    – crip659
    Commented Sep 4, 2022 at 10:28
  • Our toilet has S TRAP and it's fused with Sewage pipe. I have attached the picture in the post.
    – Amogam
    Commented Sep 4, 2022 at 13:04
  • Did I read correctly that the house is only 4 months old? Why isn't this the builder's problem to solve?
    – RetiredATC
    Commented Sep 5, 2022 at 2:47
  • @RetiredATC - Yes , He seems to be busy with projects in out of station
    – Amogam
    Commented Sep 6, 2022 at 4:10
  • 1
    You're still focusing on the wrong problem. There is likely nothing wrong with the septic tank. The problem is more likely a clog between the toilet and the septic tank. If you can't find the clog and you can't get your builder to respond, then it's time to hire your own plumber to come take a look. If he finds a problem with your builder's workmanship, then you talk to your builder about paying the bill.
    – longneck
    Commented Sep 6, 2022 at 13:56

2 Answers 2


From what I can figure out you have a problem that the septic tank is not draining into your leach field or sewer depending how things are connected. I would definitely check that out first. We never put anything into our septic tank. When we started it my father flushed a mixture of regular and brewers yeast mixed with warm water, sugar and let it set overnight before flushing it. We were ok for several years until the septic outlet tile broke. Fixing that fixed the whole thing. Our symptoms were similar but we only had one of everything.

  • Yeah , This is why I'm shocked as well.. how come just in 5 months septic tank overflew
    – Amogam
    Commented Oct 3, 2022 at 18:03

This sounds like a problem with the plumbing, not the septic tank at all. It's either not vented correctly, or clogged somehow. I'm going with incompetent plumber, since it's new plumbing and you have a seal leak on at least one toilet already (as @crip659 comments, your mason is incorrect, and not knowledgeable about plumbing.)

BTW, Once in a month , I drop Bio-Septic cleaning liquids into the toilet is just a waste of money and more likely to harm than help your septic tank. But your septic tank should have nothing to do with this problem, from the description.

  • Thanks for the post. I have some doubts for example If the issue is due to clogging then TOILET 1 only should have the problem andTOILET 2 shouldn't have any problem with the flush water. Toilet 2 sits directly on top of septic tank and there's seperate pipe that connects this toilet with septic tank.This is the fact that makes me think could it be septic tank overflowing issue but it's really hard to imagine within 5 months of moving in .. the septic tank fills up ?
    – Amogam
    Commented Sep 4, 2022 at 13:07
  • Our septic tank has open bottom and I noticed naturally the tank is filled up with 1 feet of ground water which is salty , I got to know salt water will reduce the bio activity on sludge Hence I thought Bio septic cleaner might help boost the bio activity. I'm curious to learn how bio septic tank cleaner might harm ?
    – Amogam
    Commented Sep 4, 2022 at 13:11
  • Regarding the air vent , I can see we have multiple air vent pipe ( 18 feet from ground ) and I couldn't see anything blocking the air vent pipes as well.
    – Amogam
    Commented Sep 4, 2022 at 13:15
  • I'm flabbergasted on what might be causing the issue ?
    – Amogam
    Commented Sep 4, 2022 at 13:16
  • So far I've tried Toilet Plunger and Chemical approach ( Hot water + Baking soda + Vinegar) and (Hot Water + Dish washing soap). To me it seems that it's not clogging issue , it's either Septic tank is full which is unlikely or air vent blockage I couldn't see anything blocking on the top of air vent. Is there any way to find air vent blockage ?
    – Amogam
    Commented Sep 4, 2022 at 13:41

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