Drain & Sewer Tips / Sewer Problems

That rotten-egg smell doesn't mean your house is dirty — it means sewer gas is finding a way inside. Sometimes the fix takes 30 seconds and a pitcher of water. Sometimes it's the first warning of a failing sewer line. Here's how to tell the difference.

1. A dried-out P-trap (the most common cause)

Every drain in your home has a U-shaped pipe underneath that holds a small plug of water. That water is the only thing standing between your living room and the sewer. In Colorado's dry climate, a floor drain or guest bathroom that goes unused for a few weeks can evaporate dry — and sewer gas walks right in. The fix: Pour a pitcher of water down any drain you rarely use. If the smell fades within a day, that was it.

2. A blocked or frozen vent stack

Your drain system breathes through a vent pipe on the roof. When it's blocked by leaves, a bird's nest, or frost (a real thing at altitude), sewer gas gets pushed back through your drains — often with gurgling sounds as a bonus.

3. A failed toilet wax ring

If the smell is strongest around one toilet, the wax seal between the toilet and the floor may have failed. You may also notice the toilet rocks slightly. This is a cheap fix that prevents an expensive subfloor repair.

4. Biofilm buildup in a shower or sink drain

A stink that's strongest right at one drain — especially a shower — is often bacterial buildup coating the pipe, not sewer gas at all. A thorough drain cleaning clears it.

5. A clogged or partially blocked sewer line

Here's where it gets serious. When your main sewer line is partially blocked, waste sits in the pipe instead of flowing out, and the odor works back into the house. Warning signs that it's the main line: more than one drain smells, drains are slow throughout the house, or you hear gurgling when the washing machine drains.

6. A cracked or broken sewer pipe

A persistent sewage smell in the yard, the basement, or a crawl space — especially with damp spots or unusually green patches of grass — points to a cracked line leaking under or beside your home. Colorado's freeze-thaw cycles and shifting soils are hard on older clay and cast-iron pipes.

7. Sewer gas coming up from a floor drain after backups

If your basement floor drain has ever backed up, debris can hold the trap open or the drain may be tied to a line with a developing problem.

When to stop sniffing and call someone

Try the water-in-the-drain trick first. But call a drain professional if the smell keeps coming back, affects more than one room, comes with slow drains or gurgling, or you smell it outside near your sewer line's path. A camera inspection will show exactly what's going on inside the line — no guessing, no unnecessary digging.

Smelling something you shouldn't in Colorado Springs, Monument, or Castle Rock? Drain Plumber Pro will find the source — call (719) 639-4137 for a free estimate.