A sewage smell in your basement is more than just unpleasant—it’s often a sign of an underlying plumbing issue. To solve it, you’ll need to “follow the power,” tracing the airflow and water pathways in your home’s plumbing system. By systematically identifying where the smell is coming from, you can often fix it yourself or know exactly what to tell a professional. Let’s break it down step by step.
Tools You’ll Need
To investigate and address the issue, gather these items:
- Flashlight: To inspect pipes, drains, and vents.
- Bucket or Bowl: For capturing water when testing drains or traps.
- Plumber’s Snake (Drain Auger): For clearing blockages in pipes.
- Plunger: To dislodge clogs.
- Rubber Gloves and Mask: For hygiene and safety.
- Drain Cleaner (Enzymatic or Natural): For cleaning out smelly drains.
- Utility Tape or Incense Stick: To check for airflow issues in vents.
Difficulty Rating
- No Brainer: Checking for dry traps and simple clogs in drains.
- Think About It First: Clearing deeper clogs or cleaning vent stacks.
- “F That” Level: Dealing with broken sewer lines, sump pump failure, or major venting issues that require professional help.
Follow the Power: Step-by-Step Diagnosis
1. Locate the Source of the Smell (Difficulty: No Brainer)
Start by determining where the smell is strongest in your basement. This will give you a clue about its origin.
- What to Look For:
- Is the smell strongest near a specific drain (floor drain, sink, shower, etc.)?
- Is it near the sump pump or a sewage ejector pump?
- Does it seem to be coming from the walls, ceiling, or vents?
- What to Do Depending on Your Observations:
- If the smell is strongest near a drain: Move to Step 2 and check for dry traps or clogs.
- If it’s near the sump or ejector pump: Inspect these systems in Step 3.
- If it seems to come from walls or vents: Investigate venting or hidden leaks in Step 4.
2. Check Drains and Traps (Difficulty: No Brainer)
Drains and traps (the U-shaped pipes under sinks or floor drains) are designed to block sewer gases. If they dry out or clog, odors can escape.
- What to Look For:
- Is there standing water in the floor drain or sink trap?
- Does the drain gurgle or emit odors when water runs elsewhere in the house?
- What to Do:
- If the trap is dry: Pour a gallon of water down the drain to refill the trap. Add a few tablespoons of mineral oil to slow evaporation.
- If the drain is clogged: Use a plunger or a plumber’s snake to clear the blockage.
- If the smell persists: Move to Step 3.
3. Inspect the Sump Pump or Sewage Ejector Pump (Difficulty: Think About It First)
These pumps handle excess water or sewage in basements. A malfunction can cause odors.
- What to Look For:
- Is the sump pump or ejector pump lid sealed tightly?
- Is there standing water or sewage around the pump area?
- Does the pump cycle on and off as expected?
- What to Do:
- If the lid is loose: Tighten or reseal it with silicone or a gasket.
- If the pump isn’t working properly: Check the power supply or float switch. Replace or repair the pump if necessary.
- If there’s standing water or sewage: The pump may be overwhelmed or clogged. Clear debris and test the pump.
- If the odor persists: The venting system may be the problem. Move to Step 4.
4. Investigate the Plumbing Vent System (Difficulty: Think About It First to “F That”)
Plumbing vents let sewer gases escape from your home. Blocked or broken vents can cause odors to back up.
- What to Look For:
- Are any vent pipes visibly cracked or disconnected?
- Does the odor intensify when you flush a toilet or run water in sinks?
- What to Do:
- Check vent pipes: Use a flashlight to inspect for cracks or disconnections in vent pipes visible in the basement.
- Test airflow: Light an incense stick near the drain opening while running water in nearby fixtures. If the smoke is pulled toward the drain, the vent may be blocked.
- Clear blockages: Use a plumber’s snake to clear the vent stack from the roof. If you’re uncomfortable with this, call a professional.
5. Look for Hidden Leaks or Sewer Line Damage (Difficulty: “F That”)
If none of the above resolves the issue, the problem may be deeper within the sewer system or caused by hidden leaks.
- What to Look For:
- Is there moisture or discoloration on walls or floors near the smell?
- Does the basement flood during heavy rains?
- What to Do:
- Inspect for leaks: Check the perimeter of the basement for signs of water damage or cracks.
- Test for sewer line issues: Call a plumber to run a camera inspection of the sewer line.
- Address structural issues: For major leaks or pipe breaks, professional repairs are necessary.
Preventative Tips
- Regularly pour water into rarely used drains to keep traps full.
- Seal sump pump or sewage ejector pump lids tightly.
- Avoid flushing grease, wipes, or other debris that can clog pipes.
- Have your sewer line inspected periodically, especially in older homes.
Conclusion
A sewage smell in your basement can be alarming, but by “following the power” of airflow and water, you can trace the source of the problem. Whether it’s a dry trap, a clogged vent, or a malfunctioning sump pump, these steps will help you find and resolve the issue—or know when to call in the pros. A little investigation now can save you a lot of headaches later!
