Bathroom Sewage Odor

[marinermark]

We are experiencing an occasional light-to-medium sewage odor from the front (master) bathroom in our 2005 Homes of Merit. The odor began a few weeks ago and occurs just after discharging a moderate amount of water from that toilet, kitchen sink or washing machine, which are all at the front of the house. Flushing the rear bath toilet does not result in the smell. I looked under the house from the side with a spotlight and could see no leak or discharge when the front toilet was flushed several times. The vent pipes under the bathroom lavatories don't appear to be the source. This doesn't happen every time; we may go 2-3 days between occurrances. Do you have any ideas as to the cause and resolution? Thanks for your help.

[David Oxhandler]

The most likely cause is a blocked vent. Aside form the vents under the lavs, there is also a vent pipe for the toilet in the wall that goes thru the roof, so when you flush the sewer odor vents above the home. Go up on the roof and see if some autumn leaves are blocking the black pipe above the bathroom.