Why do I smell a sewer odor in my unfinished basement?

Jackie traverse
by Jackie traverse
The basement is plumbed for a bathroom. I checked the plumbing and it all seems to be sealed, as well as the sump pump area.The others bathrooms in the home are frequently used.There is no specific time and length of day the odor lasts, but it is quite strong. It does not penetrate throughout the rest of the house. The concrete floor has been painted over as well. Help?
  8 answers
  • John John on Jan 04, 2015
    @Jackie. Try to determine if there is an air vent pipe integrated with the plumbing in question. The vent pipe usually exits through the roof and thus siphons off the offensive gases. If you don't have one you will experience 'smell-back' from the effluent gases filtering back up through the drains and toilet. One can be installed without cutting a hole if the roof by installing a vent pipe in the wall with a vent cap placed on top which you can find a Lowe's or Home Depot. I have successfully used them.
    • Marion Nesbitt Marion Nesbitt on Jan 05, 2015
      @John Not a plumber but agree. There must be a stack in the basement for the washer???? In my basement, the toilets have a pipe leading into the main stack that goes right up through the house to the roof.
  • Barbara Thomas Barbara Thomas on Jan 05, 2015
    If you are vented properly, consider a gas leak. We once had that smell in the basement of an older home and it was coming from a gas furnace. The smell eventually went through the house and we called the gas company for a check. They immediately shut the furnace down. Just a thought.
  • Glen Glen on Jan 05, 2015
    Check all your drains including the one in the floor. These are connected to the sewer line. They should have water in them which fills the trap below the floor, over time this can evaporate, if they are dry, gas can come up them. I suggest filling them with water.
  • Eloise Eloise on Jan 05, 2015
    I was told by a plumber to pour a bucket of water into the floor drain at least once a month to prevent sewer odors.
  • Simone McInnis Simone McInnis on Jan 05, 2015
    Sewer gas happens when the pipes don't get used. Just pour water down the drain.
  • Bet1058847 Bet1058847 on Jan 05, 2015
    Try putting a little water in any drain that may not have been used in a while. If the drain trap is dry it will allow sewer gas to come back up.
  • Victoria Cross Victoria Cross on Jan 05, 2015
    I had the same problem and found pouring a bucket of water down the floor drain every week kept the smell away.
  • Jackie traverse Jackie traverse on Jan 06, 2015
    Thank-you all for your information!! Extremely helpful! I will pour water in and see how that works, then I would have a plumber check the venting as John suggested. I feel a bit more educated now. Thank-you!!!