Hi, i have a confusing problem.I just installed a new toilet in place of an existing one. The promblem is when I flush the new toto toilet, my other toilet bowl almost completely empties.. The 2 toilets are basically back to back, and use the same vent pipe through the roof.(3 inch copper).No pipes were changed or rearranged and the vent seems to be clear. Anybody ever have similar problem or any suggesstion on what to try next..
thanks in advance,

Scott

dmatos

Is the new toilet a pressure assist or something? It may be that the new one pushes water through the drain much faster, so your vent which "seems to be clear" may not be clear enough. That's guess number 1.

Guess number 2 is that the person who orignally put the plumbing in messed up. Do you know how the two toilet drains are plumbed?

sjp1

HI, basically a 3" vent pipe from roof to main sewer pipe in basement. A 3" tee 2 feet above main pipe, each side goes to 1 toilet.. Another drain pipe from double sink hits right below the tee,but that has its own vent pipe..If that one was clogged would that effect toilets? i have no drainage problems throughout house.. As for the toilet ,not sure if it power assisted (whatever that is) will have to find paperwork.. thanks again
Scott

letmetellu

Flush both back to back commodes at the same time and see if this results in a possible back up. When the line is clogged past the two commodes and you flush one commode it will raise the water level in the second commode and than as the water drains it creates a vacuum in the other commode and make the water level go down. ....this is just an Idea of what might be wrong.

dmatos

PS - pressure assited toilets have a sealed tank in the back. The water in the tank is at the same pressure as the water coming into the house. If you poked a hole in it, it would spray out like a garden hose. When you flush, the water goes into your bowl much faster because of the pressure, and helps to wash things away.

A normal toilet tank is open at the top (ie, if you take the lid off, you can see the water), so the force of the flush comes from gravity alone.

speedball1

Hi Scott,

I waited to see if you had more details to offer us. A toilet bowl lowers its level for reasons. (1) a crack or hole in the bowl or (2) a vacume is produced by a lack of venting and the toilet discharging attempts to vent through the back to back toilet. I opt for door number 2. A 3" vent should handle two toilets even if a pressure assist is one of them.
I would check, first the vent and next the installation. You say, "the vent seems to be clear." How do you know for a fact that it's clear? Has it been snaked to make sure? Is the other toilet a pressure assist one? Let us know. Regards, Tom

sjp1

Hi everyone, thanks for all the info. I figured out my toilet is not power assisted,my vent is clear, and there are no holes in my bowls. I watched from above my vent and when i flush my new toilet the water rushes through the drain and some seems to go up the drain of the other toilet.( It can do this because the drains are directly across each other in the TEE.) Can this be my problem? Would this water be able to create suction in the second bowl? Or,can it be a clog after the toilet drains and in the main sewer pipe? Any Suggestions would be helpful..
Thanks:Scott

speedball1

"I watched from above my vent and when i flush my new toilet the water rushes through the drain and some seems to go up the drain of the other toilet.( It can do this because the drains are directly across each other in the TEE.) Can this be my problem? Would this water be able to create suction in the second bowl?"

Yes. If the water fills up the pipe in the other toilet then when it drains back it will set up a vacume. This will lower the level in the other toilet. (Good job of analyzing the problem.) Now what can we do about it without tearing up your drainage. Perhaps lowering the water level in the new toilets tank will lower the head pressure and volume so it drains instead of going into the other toilet. If there's a double sanitary tee picking up both toilets instead of a double combo,( combination wye and eighth bend) that could very well present a path of least resistance to the discharge and send it into the other toilet.

"can it be a clog after the toilet drains and in the main sewer pipe?"

The clog would have to be close to the double tee. A clog in a vertical stack is doubtful.

You have a interesting problem. Please keep me in the loop. regards, Tom

Firm1Tom

I also have the same problem of one toilet draining when another is flushed.
I have thee toilets in the house.
They worked great.
I decided after 30 years of use to upgrade from the 5 gallon per flush toilets to the 1.6 gallon per flush model.
Two months ago I installed the fist 2 .
They worked great the 3rd old one also worked great.
Last week I installed the 3rd new 1.6 model (all the same well known brand and model # from Home D--.
Now the 3rd toilet losses water each time any of the other 2 are flushed.
This does not happen with #1 or #2 toilet just the last one.
It also never happened with the old #3 when the other toilets were flushed.
I went on the roof and stuck a hose to the bottom in each of the 5 --2" diameter vents.
I let the water run in each for 10 minutes and went inside to hear water flowing in each of them.
I flushed all 3 toilets and let them fill.
We left for 4 days and after returning home checked all 3 and the water level was normal in all 3.
Flushed #1 and watched #3 go down 1"
Flushed #2 and #3 went down another 1"
# 2 and #3 are back to back and 2 feet apart
# 1 is 30 feet away.
Im stumped and would appreciate any suggestions
Thank you
Tom