Plumbing alteration has created vacuum in upstairs toilets


Prior to my bathroom remodel, I had a toilet flange moved in my basement to a standard 12" rough-in, since the toilet was about 5" off the wall and looked silly. The problem I have now is a vacuum in the upstairs toilet lines, such that when I flush one, the other toilet (opposite wall) sucks down water and vice versa. I believe this to be related to the plumbing alteration since the toilets seemed to work fine beforehand.

When the plumber jackhammered up the floor he noticed a split in the pipe. Because of this split he couldn't move the toilet and said he had to remove the split. BTW, he said he never sees this sort of thing. The split seems to be where the vent pipe connects to the main plumbing.

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Once he removed the split, he diverted the vent pipe (and bath sink) into the main wall pipe.

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You can see how the vent pipe now tees into the larger pipe (upstairs plumbing) and then goes into the floor where it meets the new toilet line. He seems to have tapped off the old pipe

So, now to my question. Is it obvious from this plumbing change as to why I now have vacuum in the lines? Next question, is this plumbing alteration correct?

Best Answer

Its a venting problem. Without enough volume of air to replace the volume of water moving down the pipe a suction is created. This is due to sizing or placement problems. Get a new plumber, a licensed one if your state upholds that standard. The license would separate those who say they are a plumber from those that are plumbers.