I have an addition where the toilet clogs every few weeks. You can hear it coming a few flushes before the back up with a LOT of gurgling in the pipes. I "fix it" by running the shower, and air is forced up and out of the toilet, and then a few minutes later the toilet drains and is unclogged.

After snooping here, I suspect something is improperly vented. But where do I find the vents? Are there separate vents for toilet and shower?

  • Guessing this is a house. The plumbing vent/s usually go though the roof, and can become clogged. Usually there is one main vent close for toilets/sinks/showers, but if there is more plumbing at the other end of the house, might be a second vent. Try to find a clean out(a tee with a cap) and can probably run a snake up the vent.
    – crip659
    Feb 3, 2022 at 16:14
  • Welcome. Whether you're "out of your league" or not is subjective and not for us to decide. I've removed that part of your post as off-topic.
    – isherwood
    Feb 3, 2022 at 16:53
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    Dupe : Does my toilet drain poorly because of bad venting? TLDR; No. Venting problems cannot cause slow drains. This is a very common misconception. You have a blockage.
    – J...
    Feb 4, 2022 at 15:05

1 Answer 1


Your vent, if it exists, should reach the roof (there are exceptions, as noted in comments). You can look at the roof for a short metal or plastic pipe sticking out, it may or may not have a cap. This would give you a rough idea where it is inside the house, it is likely inside a wall. Depending on the layout there may be more than one vent.

If it does not have a cap it could be plugged by something (birds, squirrels, intercontinental coconuts) falling into it - this would likely be apparent with more plumbing issues (gurgling, slow draining) at more than just your toilet, though - if there is more than one vent it could affect "half the sinks/toilets" or be limited to "just one bathroom's devices".

If you can find the vent and find a clean-out as suggested in a comment, you can try to clean it out. Have a bucket under the cleanout in case "stuff" comes out as you're working.

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    Note that there could be more than one plumbing vent based on the layout of fixtures in the house.
    – FreeMan
    Feb 3, 2022 at 17:22
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    This might [once more] depend on territory, but vents don't need to go above roof height any more, so long as they have a one-way valve. That means it could be in loft space, or just truncated on an outside wall.
    – Tetsujin
    Feb 3, 2022 at 17:27
  • Ewww... @Tetsujin. They allow venting sewer gas into the attic in your neck of the woods?
    – FreeMan
    Feb 3, 2022 at 18:01
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    It doesn't vent, it's a one-way valve, air input only. drainagepipe.co.uk/soil-and-waste/…
    – Tetsujin
    Feb 3, 2022 at 18:13
  • Ask yourself this - If the air vent is plugged, what is stopping air from entering the system from the big open toilet bowl? (hint : nothing) So the water will still go down with a blocked vent. Sometimes even faster - and it'll take the trap water with it because that's where the air is coming from. Plugged vents don't cause slow drains. Blockages do.
    – J...
    Feb 6, 2022 at 13:26

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