Plumbing – periodically pour water down the basement floor drain to maintain the p-trap water seal

basementdrainplumbingsewer

There is a sewer smell coming from my basement. There are only a couple entries to the sewer in the basement: A laundry sink that acts as the drain for a water softener (which regenerates every few days), and a floor drain.

I suspect that the floor drain is eventually evaporating the water in the p-trap, and I'm getting sewer gasses coming up. I've poured a bucket of water down the drain and it seemed like it helped, but it's difficult to tell, probably because the air in the basement doesn't get replaced much.

Is this a known problem? I can think of a few solution if so.

  1. Pour water down occasionally.
  2. Seal the drain or put a valve in it somehow – although this doesn't seem like a bright idea in case the sewer line between the drain and the city sewer has a blockage.
  3. Cover the drain with something to keep the gasses from coming up, but should the sewer have a blockage, the cover will move out of the way or float.

Best Answer

You can use something like the non-toxic RV antifreeze which evaporates more slowly than water; Or wash the basement floor occasionally.

A touch of mineral oil (the stuff sold for putting in people) may help to prevent evaporation by forming a surface film, but don't overdo that.