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 Toilet surges, septic gas let in, without any water use in house
Author: Seattle Dan (WA)

Hi All, very puzzling problem. I've never seen this before. One toilet surges to the point it 'burps' septic gas in the house. Sometimes a sink upstairs does it too, in unison with the toilet.

Here's what it looks like with a modest surge: [www.dropbox.com]

Some details:

1) The house faces the waters; it's often quite windy. I've put an 'RV vent cover' on one of the 3 vents; the top most one. I'll try covering the other vents. Some have said strong winds over the vent can cause this sloshing. The vent i used was [www.amazon.com]

2) This happen when no water is being used.

3) I am on FAST septic with a blower that runs 20 minutes on, 40 minutes off (cabin, so on a reduced duty cycle). The sloshing does not last the full 20 minutes.

4) I'll be checking to see if the septic system purge cycles coincides with this surging. Seems very unlikely to be related.

5) It does without saying that there is backup... we can run showers, flush as much as we want, etc with to problems of sluggishness of flow.

Any tips would be appreciated.

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 Re: Toilet surges, septic gas let in, without any water use in house
Author: North Carolina Plumber (NC)

Positive pressure is being trapped in the drainage system and being forced thru the toilet trap. I know of several homes where the water in the bowl will slosh around like that during windy conditions. A Sweet Air charcoal vent extension will prevent the winds from causing that much pressure in the piping system.
I've never saw it so bad that it let sewer gas escape into the home before though. What is this fast septic system you speak of ?

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 Thanks NCP :thumb:
Author: Seattle Dan (WA)

Thanks NCP. I'll look into the charcoal. I'll report back if problem is solved.

The FAST system is this one: [www.biomicrobics.com]
I live on an island, water front and the system processes waste so well the drain field is drip irrigation hose.

Edited 1 times.

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