View Full Version : Toilet needed with the 'oomph' to get a good flush through a backflow preventer.

08-08-2011, 07:06 PM
I currently have a Toto Supreme (I think that's the model name...) in my basement bathroom. We periodically get sewer backflow from the city mains and our usual method of prevention, a rag stuffed in the toilet, is getting tiresome; especially when we're not home to do it and there's a huge rain.

I bought a simple backflow preventer that mounts under the toilet but the Toto Supreme doesn't really have the oomph to get things through. I've read here that the Toto Drake has a better flow and that while it has it's drawbacks, the Gerber Ultra-Flush can get most anything down it.

I'd prefer the Toto for it's style and lesser noise but even with a wider trapway, could it compare to an Ultra-flush in getting a good flow through what is basically a purposely installed minor blockage? Short of digging up most all of my small front yard and installing a proper sewer line backflow preventer, I'm stuck with this one - but I can't have guests embarrassed by getting their junk stuck in my toilet.

My assumption is that even with a good drop and a wider trapway, the Toto might not be able to 'power through' the preventer like it would an open sewer stack and that the Ultra-Flush, with its air-pressure might be the better choice, even if it's not the most aesthetic or gentle on the ears.

Any other ideas and suggestions are welcome.

Picture of the back flow preventer:

08-08-2011, 09:34 PM
Any other ideas and suggestions are welcome.

Remove that ridiculous thing and install a proper back water valve in your sewer main!

08-09-2011, 05:51 AM
I have never seen one of those used for a toilet. I cannot see how ANY toilet would have the "oomph" to flush solids through it. They are usually used in floor drains. Was that something sold on TV after Midnight for $19.95 and you got two of them by ordering "within the next ten minutes. Just pay the additional shipping and handling fees"?

08-09-2011, 11:51 AM
How do you even seal that thing to the rest of the drainage system? It's not the right thing for your problem!

08-09-2011, 02:02 PM
The 'thing' fits between the toilet and the wax ring. Believe it or not, it works well enough, better than a rag - that's for sure since it's always there. Digging up most of my tiny front yard is not yet an option so can we answer my main question of which toilet would be most likely to push through 'the thing'. (Most of what I've read about main line back flow preventers makes them seem like a poor solution as well since any bit of food, toilet paper or whatnot will cause them to be completely ineffective against a rise in water level) 'The thing' held back a recent short surge so I'm happy enough; I just want to have worry-free flushing.

Any other positive ideas would be welcome.

08-09-2011, 03:33 PM
No toilet flushing system, gravity or pressure-assist, produces a very long-term pressure wave - it drops off almost instantly once the motion is started. This means that with any restriction, it may only push part of it over the weir. I don't think you'll find any toilet that will reliably work with that thing in the path. A toilet relies on the siphoning effect of an unbroken path once started. That thing breaks it up and really messes up the siphon, resulting in a poor flush, if at all.

08-09-2011, 03:59 PM
You can try the pressure assist and see if that works.

Runs with bison
08-09-2011, 09:36 PM
If I had an issue with backflow from the sewer main, I probably wouldn't have a toilet in the basement level. I don't mean that to be a flippant response, I'm just wondering if it would be a serious inconvenience to do without the toilet in the basement? It sounds like a considerable risk (and I vaguely remember a "Dirty Jobs" episode where they did clean up in basement that had such a sewer back up.) Are you properly insured for this sort of flooding? Again, I'm not taking a swipe at you, merely suggesting taking a bit wider view of the problem.

Is the backflow more of a "belch" of sewer gas? Or a small liquid level rise? I can't help but think of floor drains as an entry point for sewage in the event of a backup. I'm assuming that any liquid level rise is insufficient to reach the sink drain.

Good luck, whatever path you choose.

08-10-2011, 07:30 AM
I figured that toilets need to siphon well to work and that's why I thought that even the Toto Drake might not be able to power through and keep a flow with this preventer. I'll try the pressure assist and let you guys know my results, positive or negative.

The basement toilet is our most used. The basement is fully finished (and with flood/sewer insurance) and is essentially our family room. The floor is about 3 1/2 feet below grade. The shower in the bath has a ball/float type back flow preventer which has never let more than a slight trickle through - even when we had the 7.8" rain in 24 hours a month ago, a 100 year record. Unfortunately, we were too sleepy to get up and plug the toilet. Thankfully the mess was contained to just the tiled bath mostly. The sink top is nearly at ground level and has never done more than gurgle. Of course the proper solution to this is for my village to add better street sewers but until that happens...

Gary Swart
08-10-2011, 09:18 AM
Maybe I'm missing something here. It seems to me the city is responsible if the main line clogs and causes a backup. This happened to me twice a number of years ago. The city paid the damage and since then on a very regular basis, there is a crew with a power jet that checks the line that caused the problem. The real cause was a faulty grease trap in a fast food joint about me that released grease which in turn balled up in the manhole where my sewer line dumps into the city main. Point is, the city paid damages without question, and has continued to monitor their line.

08-10-2011, 03:14 PM
The operation of a pressure assisted flush verses a gravity flush isn't much different except for the complexity and noise in the pressure assisted one. They BOTH rely on siphoning to complete the flush. The way the flush starts differs - a pressure assist uses the supply pressure to shoot a jet to start the flush. A gravity flush uses the height of the tank and properly shaped waterways to create that same jet to start the siphon...once that starts, the differences are very minor. That initial assist does not continue through the entire flush, it relies on the siphon effect to finish it. Then, you have the quality of the design on the trapway, by no means are all created equal.