Toilet bowl empties when flushing another (back-to-back) toilet

[ellymae]

Burping toilet

Have a condo on top floor with a brand new Kohler Cimarron toilet in guest bath, and new Toto (either dual cyclone or Gmax? flush) in master bath. When you flush Kohler, the Toto has a big burp which spatters all over the rim. Plumber came out today and filled all sinks, tub, then let everything drain at once. Everything drained fine, but toilet still burps. Pulled the Toto and ran a camera down to see if there was a plug...all lines were clear. Replaced Toto with another Kohler Cimarron, so that both had same puddle amount. This did not correct problem. Others in the building have been having the same burping problem. The plumber explained that since this has happened only after the bigger puddle (3 gal) toilets were replaced, there is not enough water weight, therefore the burp. Also the design of the plumbing in the building, as well as the toilets being so close to each other was a factor. In his 30 years of plumbing, he has never run into something that he could not fix. He even went up on roof and dropped a penny down each vent stack.

Any thoughts or comments would be appreciated.

Ellymae

 

[WJcandee]

Are the toilets back-to-back? That's probably how your question ended up in this thread...

In other words, does the wall of your guest bath share a wall with your master?

It isn't the weight of the water that is likely the problem; it is that there is a higher velocity of the flushes in newer toilets (I say newer because they have been mandated for more than a decade). This clears the bowl with less water. When these toilets are mounted back to back with a simple cross, water from one can shoot across into the closet bend and trapway for the other, leading to water sloshing around in the other toilet. This was less likely to happen when toilets lazily-sloshed water down the closet bend and into the drain stack; the lower velocity water didn't shoot across.

 

[Sponsor]

 

[ellymae]

Are the toilets back-to-back? That's probably how your question ended up in this thread...

In other words, does the wall of your guest bath share a wall with your master?

It isn't the weight of the water that is likely the problem; it is that there is a higher velocity of the flushes in newer toilets (I say newer because they have been mandated for more than a decade). This clears the bowl with less water. When these toilets are mounted back to back with a simple cross, water from one can shoot across into the closet bend and trapway for the other, leading to water sloshing around in the other toilet. This was less likely to happen when toilets lazily-sloshed water down the closet bend and into the drain stack; the lower velocity water didn't shoot across.

Thank you for responding. Yes, the toilet does share a wall with the master, but the toilets are not back-to-back. This really has only started since switching to the 1.6 gal flush, no matter what the make of the toilet. My plumber is going to join this site, so hopefully he will chime in here shortly. This is a great forum...lots of info and answers.

 

[Jadnashua]

It all comes down to the actual fitting in the wall between the two toilets. Your situation would be even worse with a pressure assisted toilet which pushes water out faster than the gravity flush toilets. As said, the older toilets were fairly slow emptying the waste...most of the new ones, trying to do more with less, have a means to get the siphon started almost immediately, rather than the water swirling around, getting deep enough to trigger it. Toto warns of problems in their spec sheet unless the proper fitting is in the wall - but it is not unique to Toto. Kohler has the same issues.

 

[Don1227]

Same problem Installed two new toilets back to back, July 2018, different models, water sucks out of bowl only one of them when other is flushed, Plumber quoted me $950 today to change out plumbing in basement, seams a little high but I wouldn't want the job.

 

[Mitchi]

The water sill skip across and creates a wave of air that forces the water higher and then as it recedes, goes down the drain. The newer toilets with the large flush valves can do this on some back to back fittings.

So I have the same problem. The previous owner replaced the toilets. Is there any fix other than ripping up the walls/and floor? I am in a first floor condo with cement slab floor.

 

[Terry]

So I have the same problem. The previous owner replaced the toilets. Is there any fix other than ripping up the walls/and floor? I am in a first floor condo with cement slab floor.

I think you just get used to it. When they went to faster flushing toilets, this became more obvious. If you want to refill a bowl without flushing, you can lightly depress the flush lever and ease a bit of water into the bowl carefully, and then the tank refills what you released.

There is no way of knowing what is below the slab and if it would even be possible to change for the better. There are some more recent toilets out there that my flush a little slower, the ones with the 2" flush valves would have less affect than those with the 3" flush valves.