What’s That Smell? Common Causes of Bad Odors Coming from Your Drains

If you’ve walked into your kitchen or bathroom and caught a whiff of something foul coming from the sink, you’re not alone. Unpleasant drain odors are a common issue for homeowners in Watertown, Beaver Dam, Oconomowoc, and surrounding Wisconsin areas, and they usually don’t go away on their own.

In this blog, we’ll break down the most common causes of smelly drains, how to troubleshoot the problem, and when it’s time to call in the pros at Brisc Plumbing.

1. Dry P-Traps

That U-shaped pipe under your sink (called a P-trap) is designed to hold water that blocks sewer gases from coming up into your home. If a sink hasn’t been used in a while, like in a guest bathroom, the water in the trap can evaporate, allowing those smells to rise.

Quick fix: Run water down the drain for a minute or two to refill the trap.

2. Buildup of Bacteria, Grease, and Food Waste

Kitchen sinks often become breeding grounds for bacteria due to food particles, grease, and soap scum that collect in the drainpipes. This gunk can rot over time and produce a rotten egg or sour smell.

DIY tip: Pour a mixture of baking soda and vinegar down the drain, followed by hot water. Avoid chemical cleaners, they often do more harm than good.

3. Clogged or Blocked Vent Pipes

Your plumbing system has vents that release sewer gases safely through the roof. If those vents are blocked by debris, leaves, or ice (common in Wisconsin winters), gases can get trapped and escape through your drains instead.

Solution: This one isn’t DIY-friendly. You’ll need a plumber to inspect and clear the vent stack safely.

4. Sewer Line Problems

If multiple drains in your home smell bad — or if you also notice gurgling sounds, slow drains, or backups, the issue might be in your main sewer line. Tree roots, pipe breaks, or buildup could be the culprit.

What to do: Don’t ignore this. Sewer gas isn’t just smelly — it can be harmful. Brisc Plumbing offers sewer inspections and repairs to fix the issue at the source.

5. Garbage Disposal Troubles

If your kitchen has a garbage disposal, food and grime can get stuck under the blades, causing odors that rise every time you turn it on.

Try this: Run cold water while grinding a few ice cubes and lemon peels. It won’t fix a serious issue, but it can freshen things up temporarily.

Still Smelling Something Off? Call Brisc Plumbing.

Bad drain odors are more than just annoying — they can be a sign of serious plumbing issues. Whether it’s a blocked vent, a dry trap, or something deep in the sewer line, our licensed plumbers are ready to help.

📍 Serving Watertown, Beaver Dam, Oconomowoc, and nearby areas
📞 Contact us today for fast, honest, and professional service.