View Full Version : Master bath toilet splashes and bubbles when toilet in neighboring bathroom flushed!

08-02-2010, 06:09 AM
As part of our home renovation, we moved the location of our master bath toilet and installed HET flush toilets. To move the master bath toilet the contractor/plumber changed the angle of pipe under the bathroom floor (draining the master bath toilet) from a right angle to about a 15-20 degree slant. Now when the toilet in the neighboring bathroom is flushed, the masterbath toilet sometimes splashes and bubbles. Do we need to rip out the walls and redo the plumbing or is the outflow on the Toto Drake HET toilet so strong that it's worth trying to install a non-HET toilet to see if this problem gets fixed? If this is worth a try, any particular toilet we should try? THANKS!

08-02-2010, 06:28 AM
There are 2 possibilities...

Either the line has a partial blockage and it needs cleaning...


The plumbing is not up to par...

Maybe both....

08-02-2010, 06:31 AM
Thanks Redwood -- so you don't think just changing the toilet will solve it? What's the range of cost that you think it may take to fix this? Thanks, Redrover

08-02-2010, 06:40 AM
It has nothing to do with that toilet. Either there is a partial clog in the main line, affecting both bathrooms, or slight chance of an issue with venting, but really my money is on the clog.

08-02-2010, 07:43 AM
Thanks Jimbo, how much do you think it'll take to get a plumber out to fix an issue like this and how do they make the right diagnosis?

08-02-2010, 08:22 AM
The more likely possibility is that the piping under the floor is done incorrectly, in which case there may not be an easy cure, and that is something a plumber may not be able to diagnose directly. He may have to eliminate all other possibilities first, leaving that as the only other choice.

08-02-2010, 08:36 AM
Thanks HJ -- when I called the plumber who did it, he said it may be because of the high flow toilet which is why I was wondering if I just changed the toilet my problem may be solved... Would you call back the plumber to fix or is this a quality control issue that says I shouldn't be using this plumber again?

08-02-2010, 08:49 AM
I think he is feeding you a line about a "HIGH FLOW" toilet. HET stands for High Efficiency Toilet, which means LOW flow. Even if it is a pressure assist, that should not in anyway affect other fixtures on the line. If it does, that would point again to a clog, or a vent issue.

08-02-2010, 08:49 AM
The only time I have ever seen a high performance toilet affect other fixtures was with sub-par plumbing....
Switching to a weaker flushing toilet may eliminate the symptom but the plumbing will still be wrong...
Usually involving the use of an improper fitting somewhere.

Whether your plumber will fix the problem or, not depends on whether you should use him...

Some plumbers have a camera which can be sent either through the toilet or, down the line with the toilet removed to inspect the pipe. Chances are if a camera is put through the toilet that causes the problem you will see the camera take a path directly toward the other toilet indicating an improper fitting used.

The flow should be directed down the drain not to another fixture.

08-02-2010, 11:18 AM
Thanks Redwood and Jimbo -- guess I should call a plumber to take a look and help diagnose it or we may just live with the problem for a while longer -- if you or anyone else has any other suggestions I'd appreciate it.

08-02-2010, 11:32 AM
Some of the new toilets flush with less water, but much quicker.
Care should be taken if they are installed on a cross fitting, sometimes flushing one toilets causes the water to skip over the cross fitting and push water and or air up in the bowl next door. That's your bubbling and splashing.

It still works that way, but it does mess with the bowl level on the bowl next door.
The older toilets with the 2" flush valves don't "skip" the water so much.

08-03-2010, 08:23 AM
The high velocity water is only in the toilet, once it enters the larger drain pipe it should not create any more pressure than any other toilet.

08-03-2010, 08:39 AM
Take a look at the bottom of page 2 on this linked spec sheet for a Toto Drake. (http://admin.totousa.com/Product%20Downloads/SS-00355,%20CST743S,%20V.02.pdf)

I suspect that may be what your plumbing looks like.

08-03-2010, 10:44 AM
"The high velocity water is only in the toilet, once it enters the larger drain pipe it should not create any more pressure than any other toilet."

I guess I should upload video of this in the real world for hj to see.
Yes, with the 3" flush valve toilets, the water will skip across the fixture cross and enter the opposing arm, forcing air and water up into the next bathroom toilet. Not a super big deal, but it does happen.

08-03-2010, 01:23 PM
How many times do I have to repeat that a fixture CROSS is NEVER used in good plumbing systems, nor do good plumbers use them there. The "proper" back to back fixture fitting will NEVER allow water to cross over. A an aside, I just came back from unplugging a main sewer. The geniuses who installed the cleanout riser put it into one side of a sanitary cross and connected the other side to the new bath in the addition. Guess who made some succinct comments about the ancestry of whoever did it, when my snake went right across and up the bathroom vent. And while I was digging down to the main line to install a new cleanout riser, knowing the whole system was full of water up to ground level, which would then fill my hole as soon as I cut the pipe.

08-03-2010, 01:40 PM
"The "proper" back to back fixture fitting will NEVER allow water to cross over."

Yes. This is true.
They may not have the right fitting in there.

I plan on pulling drywall on my home and seeing what it was plumbed with. I'm going to change whatever they used, because it's not working like I would like it.
Not a deal killer, but with the new fixtures, it becomes more obvious.

08-03-2010, 01:41 PM
Thanks for all the input! I do think the plumbing looks like what you said it looks like Redwood. What's our most economical option to fix this? The toilets work it's just irritating to have it splash and bubble every so often. You guys are great!

12-30-2010, 07:45 AM
All, thanks again for the input. I finally had a plumber come by and showed him pictures of the wall before it was closed up and he believes it's because the toilet while it meets code, was not properly vented when it was moved and thus is having the problem. For now, we're going to live with the problem as he said it would involve breaking down walls to get the venting correct... how can something technically meet code yet still have problems! Seems like then the code is wrong!

04-07-2011, 09:39 AM
Had a plumber fix it and he added the proper venting and the problem has been solved -- no bubbling. you can still see that the other toilet is being flushed if you look at the water, but it certainly doesn't bubble and splash. thanks again for all the input!

Tom Sawyer
04-07-2011, 05:11 PM
It wasn't a venting issue, I can guarantee that much.

04-08-2011, 01:45 PM
IF the venting worked then it cured the symptoms, NOT the problem. And proper venting would have required breaking open the floor to access the drain line, NOT doing something in the walls. How about a picture of what the UNDERFLOOR pipes looked like before the concrete was poured, because THAT is where the problem is.