Does your basement smell a bit musty, dirty, or sewer-like, even though you can't find any leaks or another explanation for the odors? If you are confident you do not have a sewer leak, then you may be having trouble with the floor drains. The drains could be clogged with grime, or they could have a little stagnant water in them, which is causing odors to waft through the home. Thankfully, this is a problem you can typically handle on your own by following these steps.
1. Try pouring water down the drain.
To see if the drain is blocked or not, try pouring a small bucket of water down it. If the water flows down the drain freely, then you know there is not a blockage. However, the odors still may be coming from the drain because of grime accumulation and stagnant water sitting in the P-trap.
If the water does not flow down the drain, then you may have a minor blockage to deal with. Try removing the grate from the top of the drain; it should come off easily, allowing you access to the collecting area and P-trap.
2. Snake the drain if needed.
You only need to complete this step if water did not flow down the drain in step 1. Buy a small drain snake from the local hardware store. You do not need the thick, industrial-sized snake a plumber would use; this might damage the drain. There are even flat, plastic drain snakes sold for a few dollars at some home improvement stores; this type will work here.
Insert the snake into the drain, turning it clockwise as you do. Then, when the entirety of the snake is down the drain, pull the snake back up. It should bring grime and sludge along with it.
3. Rinse the drain with vinegar and baking soda.
Follow this step whether or not you had to snake the drain. Pour about a cup of baking soda into the drain; there's no need to measure. Let it sit for about an hour, as this will help neutralize odors. Then, follow up the baking soda with 2–3 cups of white vinegar. The mixture will foam up and may make a mess on the basement floor, but just be patient and let it work its magic. Don't disturb it for at least an hour.
4. Pour clean water into the drain.
Once the baking soda and vinegar mixture has stopped foaming, follow it up with a bucket of water. The water will rinse any smelly particles away with it. Plus, the water will fill the P-trap, replacing the stinky, dirty water that was once there. Make sure the drain is flowing freely at this point. If the water still seems to be flowing very slowly, you may want to call a plumber and have them take a look at the drain. Sometimes, basement drain pipes can become damaged or compressed further down the line, leading to backups and blockages.
5. Top the drain off with oil.
After flushing the drain with new water, clean up any spills around it. Then, pour about 1/4 cup of cooking oil into the drain. This will seal off the top of the water resting in the P-trap so that if that water does become smelly and stagnant, the odors do not travel up into your home. The oil also prevents the water from evaporating, so your drain does not dry out.
Follow the steps above, and your basement drain will be a lot more pleasant. You may wish to repeat this process yearly as a preventative measure even if you don't notice any overt odors. For additional advice, contact a company like Complete Plumbing.