Flush, burp, flush, burp, flush... WTF?

June 12, 2011 11:39 AM

Moaning Myrtle is living in my toilet. Please help me debug.

I thought I understood how toilets work but this has got me baffled. To reproduce bug:

1. Flush toilet. (flushes like a normal toilet)
2. Wait 0-10 minutes.
3. Flush again.

The second flush invariably starts with a dramatic belch as an air bubble comes up the trap (or from somewhere else, I guess) and bursts out of the water in the bowl, occasionally sending water several feet into the air. The next flush is back to normal, followed by a burp, etc. I can repeat this pattern all day long.

Fun extra debugging info:

• If I wait longer between flushes (say, more than 15 minutes), the burp doesn't happen.
• If I pull the handle slowly, the burp can be minimized, sometimes to near-undetectable levels (that is, no or very little air moved at all, not a reduction in airspeed).
• This is a normal (except for being haunted) float/flapper toilet setup.

posted by range to Home & Garden (2 answers total)

Check your vent stack. Sounds like it's mostly blocked.
posted by scruss at 12:02 PM on June 12, 2011 [1 favorite]

Sounds to me like you have a partial blockage of your drain line. The water is backing up in the pipe and pushing an air bubble back into the toilet. Waiting 15 minutes allows the pipe to drain past the blockage.
posted by Knappster at 12:03 PM on June 12, 2011 [1 favorite]