CAUTION: Sewer gas in through basement sump

[Jerry in MN]

Just letting all of you know that sewer gas can back up not only because a rooftop sewer vent can plug up with ice, but also because the water level in the sump could be too low.
Yesterday at least four, if not all five, adult family members who stayed at my folks' guest house complained of having a headache. So one of them went up on the roof to see if the sewer vent was plugged; it wasn't. They told my dad and, after pondering what could be causing the headaches, he remembered that during times of dry weather and little water use from clothes washing, showering, etc. the water level in the sump can get low enough so that sewer gas can be drawn in.
So, if you suspect a sewer gas problem the cause could be that the sump water level is too low to provide an air lock from sewer gas. Of course this can be fixed easily by supplying enough water into the sump to cover the pump and any other potential places for sewer gas to come in.
I hope this helps someone out there!

[tiogacounty]

I had a conversation with a building inspector about this recently. He recommended that the trap be filled with vegetable oil. He claimed that it will not evaporate, and it eliminates the need to remember to add water to a potentially dry trap. I never tried it, but it makes sense. Good luck.

[Jerry in MN]

Originally Posted by tiogacounty

I had a conversation with a building inspector about this recently. He recommended that the trap be filled with vegetable oil. He claimed that it will not evaporate, and it eliminates the need to remember to add water to a potentially dry trap. I never tried it, but it makes sense. Good luck.

Interesting, maybe a thin layer of vegetable oil on top might be enough? I'll pass that on to my dad.

[michael.hickman]

Yes, I was just going to post about the vegetable oil trick. The floor drains in our restroom at work sometimes would go dry and let the sewer gases in. The vegetable oil saved the day. I still would check the drain routinely just in case of evaporation.