Why Does My House Smell Like Sewer?

The Most Common Cause: A Dry P-Trap

Most fixture drains have a curved section of pipe, the P-trap, that holds a small amount of water to block sewer gas from coming back up through the fixture. If a drain is not used often, like a guest bathroom or a floor drain, that water can evaporate, leaving a direct path for odor. Running water down the drain for a minute is often enough to refill it and resolve the smell.

Other Possible Causes

If refilling P-traps does not help, a few other sources are worth considering:

• A blocked or damaged roof vent stack, which normally lets sewer gas escape safely above the house
• A worn wax ring seal under a toilet
• A crack or blockage further down the sewer line itself

Is Sewer Gas Dangerous?

In small amounts, sewer gas is often just a nuisance odor, though it can irritate the eyes, nose, or throat or cause headaches in some people. In larger, sustained amounts, or in enclosed spaces, it can pose a real health and safety concern, so a strong or worsening smell that does not resolve with simple fixes is worth taking seriously rather than just masking with air freshener.

How to Narrow Down the Source

Notice which room or fixture the smell is strongest near, whether it changes after rain, and whether it is constant or comes and goes. This information helps a provider diagnose the cause more quickly if you do request a connection.

When to Request a Connection

If refilling P-traps throughout the house does not resolve the smell, or if it is accompanied by slow drains, gurgling, or visible sewage backup, it is a reasonable time to request a connection with a local provider rather than continuing to guess at the cause.

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