How Do You Get Sewage Smell Out of a Basement?
Last updated October 26, 2026
The short answer
Find the Source First
A sewage smell in your basement is a sign that something is wrong, not just a nuisance. Check for obvious leaks around toilets, pipes, and floor drains. Look for standing water or damp spots on walls and floors, and sniff around baseboards and corners where odors can hide.
Sometimes the source is outside, like a clogged sewer line or a blocked vent pipe on your roof. If you cannot find the source yourself, a plumber can inspect your drainage system. In St. Petersburg, heavy rains can overwhelm sewer systems, so a backup might be the culprit.
If the smell is strong or you suspect a sewage backup, do not enter the area without protection. Sewage contains harmful bacteria. Open windows for ventilation, turn off any HVAC system to avoid spreading odors, and call a professional for a thorough inspection.
- Check toilets, pipes, and floor drains for leaks
- Look for damp spots or standing water
- Inspect the roof vent pipe for blockages
- Smell around baseboards and corners
- Consider a sewer line clog or backup
- Ventilate the area before investigating
Clean Up Any Sewage Spills
If you find sewage or contaminated water, remove it carefully. Wear rubber gloves, boots, and a mask. Use a wet/dry vacuum to extract liquids, then dispose of the waste properly. Do not mix sewage with household cleaners, as that can create dangerous fumes.
After removing the bulk, wash hard surfaces with a disinfectant. Use a solution of bleach and water, but never mix bleach with ammonia. Rinse thoroughly and dry completely. Porous materials like drywall, carpet, and insulation that touched sewage usually need to be removed and replaced, because odors and bacteria persist.
For a large spill, or if the contamination is widespread, local water damage pros have the equipment and experience to handle hazardous cleanup safely. They can also identify hidden moisture that might cause mold growth later.
Dry the Basement Completely
Moisture is the main driver of sewage odors. After cleaning, dry the area as much as possible. Use fans, a dehumidifier, and open windows if weather permits. In a humid climate like St. Petersburg's, drying can take longer, so be patient and keep air moving.
Check for any hidden moisture in walls, under flooring, or in crawl spaces. A moisture meter can help you find damp spots. If you cannot dry the area within a day or two, you may need to remove materials that stay wet, like insulation or carpet padding.
Remove Odor Sources
Even after cleaning and drying, some materials will hold onto sewage odor. Drywall, wood, carpet, and concrete can absorb smells. In many cases, the affected materials must be removed and replaced. This includes cutting away sections of drywall above the water line and pulling up carpet and padding.
For concrete floors and walls, you can try a specialized odor neutralizer designed for sewage. These products break down odor-causing compounds rather than just masking them. Apply according to the label, and allow time to work. If the smell persists, the concrete may need a sealant or professional treatment.
Do not try to cover the smell with air fresheners or bleach. That only masks the problem temporarily. The real fix is removing the source of the odor, which may involve replacing materials or repairing the plumbing.
When to Call the Pros
If you cannot find the source, or if the smell returns after cleaning, it is time to call local water damage pros. They have specialized equipment to detect hidden leaks and moisture, and they can perform a thorough cleanup and restoration. They can also handle sewage cleanup safely, including disposing of contaminated materials.
Before calling, check your insurance policy to see if sewage backup is covered. Some policies include it, but many require a separate endorsement. Policies vary, and your insurer decides what is covered. If you have a backup, document the damage with photos for your claim.
The cost of professional cleanup depends on the extent of the damage, the materials affected, and the size of the area. It often ranges from a few hundred to several thousand dollars, but the final price depends on your specific situation. Getting a detailed assessment from a pro helps you understand what is needed.
Talk to someone now
Phones are answered 24/7 for St. Petersburg and nearby communities.
Call Now (727) 308-5518Frequently asked questions
Can I use bleach to get rid of the sewage smell?
Bleach can disinfect hard surfaces, but it does not eliminate odors from porous materials. It also can be harmful if mixed with other cleaners. Use it carefully on non-porous surfaces, then rinse and dry. For odor removal, you need to remove the source and possibly replace materials.
How long does it take for the smell to go away?
It depends on the source and how well you clean and dry. If you remove the source and dry thoroughly, the smell may disappear within days. If the source is hidden or materials are contaminated, it can take longer. Professional treatment may be necessary for persistent odors.
Will a dehumidifier help with the sewage smell?
A dehumidifier can help by reducing moisture in the air, which makes odors less noticeable. However, it will not remove the source of the smell. You still need to find and fix the underlying leak or backup, and clean and dry all affected areas.