Single-family Florida concrete block home built in 1979, city water and sewage.

Hallway bathroom toilet flushes great, quickly swirls, drains completely and quickly, refills.

Master bedroom toilet, however, nearly fills to overflowing and then very slowly and unenthusiastically drains. Unlike the hallway bathroom there's no satisfying swirl followed by that climactic gurgle as the toilet sort of catches its breath. Flushed it and heard no sounds from the shower drain; shower and sink both in the master bedroom drain quickly. While sitting in the hallway bathroom after flushing the bedroom, no bubbles nor gurgling from the hallway bath tub nor sink drains.

Tried plunger, sink auger, toilet auger, no significant effect. Tried Liquid Lightning™ (sulfuric acid), negligible difference after a full bottle. Went up on the roof to look down the vent, no sign of nesting squirrels or debris at least within sight of my fairly bright LED flashlight.

Have a few trees, including a big pine tree near where the drain line goes to the street in front of the house, as well as a hickory tree and a couple of sweetgums farther away from the drain to the sewer. Could this be root intrusion even though only one toilet is affected?

  • Which toilet is closest to the street sewer?
    – Kris
    Feb 21, 2021 at 2:44

2 Answers 2


In a word, no, it can't be a root problem on the main line if it's only one of the two toilets that backs up.

It's a drain or vent problem local to that toilet, or possibly something IN that toilet which is blocking flow but eluding the auger/snake. Think toothbrush, toy, ball, whatever: flushed and caught in the trapway rather than passing through.

You might want to call in a service with a drain camera. Or you might want to try removing the toilet, taking it outside, and ensure that flow through it is clear, turn it upside down and run water through it backwards, see if anything comes out or you can see anything in it. Also verify that the backup occurs (or does not) if you pour a bucket of water down the pipe, without the toilet. That should settle toilet .vs. pipe and is easier than you might think - it also gives better access to snake the line from the toilet.

  • If the good flusher has a long run of 3-4” pipe to flush into and the bad flusher is flushing much closer to a partial blockage that could explain it.
    – Kris
    Feb 21, 2021 at 2:49
  • 1
    Accepted as answer. Upon calling a plumber it turned out to be a root that had broken into the pipe just under the affected toilet! They cut away the root, applied some root killing compound, then repaired the pipe and sealed things back up. Toilet has been flushing normally ever since. Thanks for the suggestions! Mar 28, 2022 at 19:38

A new toilet solved my slow flushing old toilet problem. The holes around the inside top of the bowl that allows water from the tank to flow get clogged over time.

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