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Shallow P-trap with Floor Mount Toilet or Wall Hung?

Posted by GreenDog194 (My Page) on
Tue, Jul 10, 12 at 4:38

(Cross post from plumbing forum.)

When the contractors/plumber re-did the ground floor foundation in our remodel (adding radiant heat floors, and re-doing our plumbing drains to re-configure two bathrooms and a laundry room), they set everything 6 inches BELOW where the sewer line connects to take everything out of the house. Mind you, we never had a problem with our system before the remodel. Somehow the inside and the outside used to meet up just fine.
It was not an option to re-dig the newly re-lined sewer line all the way to the street some 60-100 feet away and 18 feet deep. So, they re-dug our new foundation, and re-set the waste lines.

The City inspector said, "I don't want to see it," (whatever that means, all I know is that he has not put his blessing on the new set-up -- a red flag in my mind).

Now, there is a toilet that supposedly is causing all the trouble. It is actually now closer to where the line connect with the external sewer line (so further "down slope" than before) -- before, the sewer line under the house was longer because this toilet was farther away (never a problem before). Apparently, now there is not enough room to put a normal P-Trap below our new Toto low flow toilet. So, the plumber put in a "shallow P-Trap." from my visual inspection this evening, I would guess there is 6-8 inches between the ring that will be visible on the tile and where the waste pipe starts to go horizontal under our slab and off to the municipal system. The plumber wanted to let us continue to use the floor mount toilet, rather than having to go to a wall mount system. [Toto or Geberit?] For some reason, my instinct says "WAIT"! (Shallow P-trap and toilet -- will it flush properly? Will stuff gurgle into my tub? Will it smell? Am I worried for nothing?)

I also suspect that the line under our foundation is now set at a more shallow slope than what Code requires to make up for that 6 inch miss. For an about 20 foot run, making up even 3 inches sounds like a much more shallow slope! (Bad combo with low flow toilets -- without slope what will move waste along?)

The contractors have backfilled over the pipe with gravel, and set some re-bar, but they have not yet re-poured the concrete.

Can anyone educate me on what might be going on here? Offer recommendations? I do not want a life time of misery with this set-up.

I'm happy to answer more questions. Clearly, I'm no plumber, and have no idea how best to describe what is going on -- other than it is COSTLY and FRUSTRATING and I'm out of trust!!

Follow-Up Postings:

RE: Shallow P-trap with Floor Mount Toilet or Wall Hung?

A separate trap under a toilet? A toilet has it's own trap. Double-trapping is no longer permissible in any code with which I am familiar. And it has always been true that sewage does not flow uphill by gravity.

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