I live in a two storey house with 3 toilets (two on second floor and one on the main floor) the main floor toilet after flushing drains to a low level . I have inspected for water under and around toilet and even underneath in basement and now water , I have replaced the fill tube and the gasket between tank and bowl. if the vent was restricted would that not affect all toilets. any thoughts

  • There may be separate vent pipes for the various sinks and toilets. If all three of your toilets were arranged such that the two upstairs were back to back and the one on the first floor was directly under one of those upstairs then it is possible that they are all served by one vent stack. Since the symptom that you are seeing is often caused by vent issues your down stairs toilet may very well be on a separate vent.
    – Michael Karas
    Commented Jul 13, 2019 at 21:34
  • thanks for the input only have one vent stack and one of the upstairs is above the one downstairs I will keep trying Commented Jul 13, 2019 at 21:48

1 Answer 1


"after flushing drains to a low level"

The level in the bowl after flushing is determined by:

  • the length of time the flapper is held open (not open long enough = no flush, inadequate flush, or low water level in bowl after flush)


  • the bowl-filler function of the fill valve in the tank/cistern. Commonly, the bowl-filler function is arranged such that a hose directs water into the bowl (usually via the overflow tube and rim clean holes) during the entire time the fill valve is open. Some fill valves allow adjustment of the bowl-filler duration/flow/volume.

If it were a venting problem, it would occur at random times (or specific times if related to other usage of drains), rather than only when the toilet in question were flushed...

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