Hello all, I have a bit of mystery and looking for plausible explanations...

I have a typical/small 1960's bi-level. The whole waste system I think is pretty simple. Upstairs I have kitchen, full bath, and smaller master full bath with shower stall. Downstairs I have a 1/2 bath and laundry room. The main waste stack appears to be 3" copper pipe, drains out to a septic about 10' or so from the house.

It doesn't happen all the time, but often enough when someone flushes a toilet upstairs or takes a shower, the toilet down stairs bubbling from some kind of back pressure. I've never observed any system issues when the laundry room is used.

I am not sure how this came to be. When I bought the house in 2004 everything seemed to work fine. At that time I lived alone. I never used the downstairs bathroom much at all, and noticed over the years that the flushing got slower and slower. Eventually had a family that increased load on the upstairs water use. The only changes I ever made to the house was to replace 1 toilet upstairs with low flow, and re-do the shower stall; at the time that was done, everything in house seemed to work fine.

Come pandemic time I started working from home and using the downstairs bathroom more often. The slow flushing has been getting better over time, but I still notice the bubbling when shower/toilet is happening upstairs.

I have no way to know for sure but I suspect maybe the waste stack is occluded somewhere just enough to allow water in the 3" wide pipe to back up and create the pressure needed to force that downstairs toilet to bubble up.

Not sure what to do about it. I am thinking maybe get a plumber here to roto-rooter the whole waste stack out to the septic.

Any thoughts or advice appreciated.

Thanks!

-- J

 

When was the last time the tank was checked/emptied ?
Typically backpressure is caused when the incoming sewage has no place to go.

 

Agree, you have not stated anything about the condition/maintenance of the septic system.

Also vent stack might be something to look at, if plugged they can cause bubbling and burping of air.

 

Thanks for the replies.

I usually get the tank pumped every 2 years, I do still need to do that this year. Perhaps I can pop the lid off there and take a look. I never had septic issues, but who knows.

I'll have to dig around and see where the vent pipes are, I honestly don't know where they are or where they enter the system.

Thanks

-- J

 

The vent pipes for your plumbing will be up to the roof thru the inside of the house.
There is usually a vent over each bathroom and possibly the kitchen.
If the bathrooms are stacked they will share a vent.

 

There isn't much to see if you open your septic tank. In normal operation they are 90%+ full. If it is full up to the lid that is a problem.

Because you have a slowly worsening problem you need to consider a clog is slowly building somewhere, possibly in the line between the house and septic tank. Another common problem is ground settling or movement that can change the pitch of the drain line or pinch it.

You can't see inside your vent system. The best you can do is go on the roof and snake, router or jet down from the roof vents to insure that they are clear. Unfortunately multiple vent lines often combine before going up and through the roof so inspecting and cleaning them all can require some skill or a camera.

 

I agree with the others. Gurgling 90% of the time means a partial clog somewhere in the drain lines. It could be in the drain pipes, the house trap (if you have one), or a filled septic.

Since it affects pretty much the whole house, I'd start with your septic company. They should be able to check the tank and run a snake up your main line in one visit (and one charge). Or of course if you're willing to snake yourself, we can help walk you through it.

 

Thanks all for your input so far.

I was (finally) able to pop my spetic tank lid. It seems like a fairly wide tank so I can't see the pipe coming from the house. However, I ran some flush tests and I can definitely hear the effluent flowing out, dropping down, splashing into the tank. So I think that rules out a filled-up tank.

Next I'll need to look at the vent pipes but I think that's going to be more of a danger issue.

I found my clean out, so perhaps snaking up & down from there might be helpful. Is there any kind of special equpment I should look for to do that?

How would I know if my house has a "trap"? I would estimate that the distance from my cleanout to the tank is less then 20' and I'm not sure what I would look for in finding a trap.

Thanks all!

 

Most septic tanks have at least two lids. They are usually close to the ends of the tank so there is access to the inlet and outlet pipes.

Traps are generally located inside the house near each fixture. Some older houses had a trap on the main drain line near where it entered the house but that has not been done for many decades. Most residences do not have grease traps on the drain lines.

For a main drain line a powered drain auger is the best. You can rent them from tool rental stores. You can also use a drain cleaning rod. Alone the rod is very limited in a large 3 or 4" drain line but you can make a "snaggle" with coat hangers for the end. You want the snaggle big enough to scrape the sides of the pipe.