Septic Tank Odor in Bathrooms

Hi All-
Totally random question here, but I’m having intermittent septic-type odor in my 2 bathrooms (we do have a septic tank). I recently had the tank pumped & sludged, but I still have the issue. No slow drains, blockages, backup, leaky faucets/toilets, etc. I made sure the vent line is open so the tank can breath (looked down the vent pipe and can clearly see the top of the water line in the tank). It just seems like it picks a random time to “burp” up through my shower or sink drains in the bathrooms, which are closest to the septic tank, and never through my kitchen sink, which is further away from the tank. Then the smell goes away, but its awful. It seems to be more common after no water has been used for a while (notice early in morning, or later in day when everyone gets home, but hasn’t used a sink or toilet yet). The company that pumped it said they didn’t see any problems and said it was “a treat to pump compared to most of their jobs.” Any ideas on what could be happening? I do have one sink on the system that has a broken drain pipe and has been plugged off and not used for at least 2 years, but this problem only recently started. Thanks for any suggestions!

Mike in Phoenix, AZ

I have a feeling that the water that is normally held in the drain trap is evaporating with the drier air this time of year. Run water in faucet and shower once in while will fill it back up.

Had this problem in our guest bathroom when it wouldn’t get used often enough. Run some water daily and I bet your problem will go away.

Check your roof vent.

These toilets, sinks & showers get used on the daily, morning and night. I’ll check the vent(s) on the roof. As far as dry air this time of year, yes, it is dry, but this was happening sometimes in August & September as well, much more humid. Thanks for all the feedback so far!

My guess would be venting. Sometimes in the winter with heavy snows,the vent over my bathroom closest to our septic tanks gets plugged up and the shower and toilet will will sometimes make funny noises yet the sinks and toilets at the other end of the house are fine.
Soon as I clear that vent it goes away.

I’ll check the venting on the roof, but certainly no heavy snows here in Phoenix, lol. Should be about 70F today!

Mike V wrote:

I’ll check the venting on the roof, but certainly no heavy snows here in Phoenix, lol. Should be about 70F today!

We’ve snaked squirrels, birds, leaves, and some weird debris out of the VTR pipes. Additionally, you can possibly get some solids that stuck where the vent pipe intersects with the drain.

Recently my dad accidentally flushed a wash cloth and it stuck in the pipe fitting where the 2” VTR pipe hits the 3” drain. Waste drained but we had gas “gurgling “ when you flush

Make sure you don’t have one of those under the sink vents. I’ve seen these stick open and allow smells into you house. Usually located right after the P-trap.

Had Sept gas odor on main floor laundry especially on windy days. Couldn’t figure it out. Thought I could smell septic gas also in mechanical room in basement. Placed plastic wrap over floor vent in basement and it would have gas under it. Person who installed or worked on plumbing removed plug from drain. Why i smell gas on level above and across house I don’t know but plumber replaced plug and problem fixed.