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Diagnose the Vent Issue — Inspect and Clear the Plumbing Vent Stack

Beginner

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How to Troubleshoot a Toilet That Gurgles When a Shower is Draining · Step 4 of 6

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To confirm a blocked plumbing vent, have a helper flush a different toilet or run a sink in another part of the house. Watch the water in the bowl of the toilet you suspect has an issue. If you see significant bubbling or gurgling in the water, it confirms that the system's vent stack is likely clogged, causing air to be pulled through the toilet trap instead of from the roof vent.

Goal: Plumbing

  • This test works with any fixture. You can run a washing machine or a shower and look for gurgling in a nearby toilet or drain.
  • Do not mistake the normal sounds of a toilet refilling for the gurgling caused by a blocked vent. The gurgling from a vent issue will be more pronounced and consist of large air bubbles.
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FAQs

How long does this project typically take for a beginner, and what's the hardest part?

The initial steps like plunging and snaking the shower drain might take an hour or two. However, the most challenging and time-consuming part is often inspecting and clearing the plumbing vent stack on the roof, which could take half a day including setup, safety precautions, and cleanup. Patience and a systematic approach are key for a beginner.

What are the most important safety precautions I should take, especially when working on the roof or with drains?

Always wear safety glasses and heavy-duty gloves to protect yourself from drain debris and potential splashing. When accessing the plumbing vent on the roof, ensure you use a stable ladder and, if possible, have someone spot you for safety. Avoid using harsh drain chemicals, as they can be dangerous and may react adversely if you later need to snake the drain.

What's a common mistake people make when trying to fix a gurgling toilet, and how can I avoid it?

A common mistake is only focusing on clearing the toilet or shower drain and overlooking the plumbing vent stack. Even if a shower drains slowly, a gurgling toilet often indicates a negative air pressure problem caused by a blocked vent. Ensure you systematically check and clear the vent stack if initial drain clearing doesn't resolve the gurgling issue.

Do I really need all the listed tools, especially the drain auger and pipe wrench, or can I get by with just a plunger?

While a plunger is your first step, a drain auger (plumbing snake) is often essential for effectively clearing deeper clogs in the shower drain. A pipe wrench is important if you need to open the main sewer line cleanout to inspect for blockages. You'll also definitely need a sturdy ladder, flashlight, and garden hose for inspecting and clearing the vent stack on the roof.

Transcript
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Don't see he heard us. Go ahead and flush it, Drew. That is us flushing the other toilet in the house and the air is coming up here. So that means we have a vent that is not working. Now we're on the hunt for a vent that is blocked. All right, and just let you know, when you start seeing that bubbling anywhere else, you got a vent that's not working, so keep that in mind.

Auto-generated transcript. May contain errors.