I finally have 2 upstairs toilets working after a lengthy bathroom remodel. What I noticed is when one toilet is flushed, the other toilet water level goes down, almost all the way. The lower level toilet is not affected.

Both toilets flush fine and there are no clogs. After flushing sometimes the water level floats up and down a bit.

From what I've gathered so far this is related to improper venting. I got on the roof and can't see any obstructions in the vent. I read about a technique for flushing by using a garden hose, but snow is preventing trying that now. Also I in the basement it looks like I can unscrew a cap on the pvc pipe to see if there's a clog.

This past year my basement flooded about 6", so perhaps that is related. Also had a new roof installed, so not sure if they dropped anything down the vent.

  • 1
    Sounds like you are on the right track investigating the vent. When toilet 1 is flushed and toilet 2's water level drops it tells me that flushing 1 is creating a vacuum that's sucking water out of 2; and, this shouldn't happen if the vent is operating properly. So, running a water hose down the vent may dislodge an obstruction that will clear the vent.
    – getterdun
    Jan 28, 2014 at 0:29
  • It's more likely the venting issue is due to the remodelers failing to install the correct vent piping, rather than the blockage of an existing vent. Was this project permitted and inspected? Done by a competent plumber?
    – kreemoweet
    Jan 28, 2014 at 7:29
  • Well the remodel was just tile, and painting. It took while because I did some of hit. No plumbing changes other than rough-in valve
    – Andrew
    Jan 28, 2014 at 14:54
  • @Andrew: If the plumbing was not changed and the problem definitely wasn't there before the remodel, then it sounds like it is definitely some temporary blockage that you should be able to clear. Jan 28, 2014 at 16:47
  • 1
    I checked the vent stack and it's completely clear. I sprayed a hose down it for a while. There were no plumbing alterations upstairs but there was one downstairs in the basement which I think may be responsible
    – Andrew
    Mar 28, 2014 at 4:35


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