Why Does My Home Smell Like Sewage Sometimes?

The most common cause of an intermittent sewage smell is a dry P-trap. These curved pipes hold water to block sewer gas. If a fixture like a floor drain or guest bathroom sink isn't used often, the water evaporates and gas escapes. Pour a cup of water down each drain to refill the trap and see if the odor fades.

Also check for leaks around toilet bases and under sinks. A slow drip can saturate wood or drywall, creating a musty, sewage-like odor. Run your hand along pipes and feel for moisture. If you find dampness, dry the area and watch whether the smell returns. If it does, the leak may be hidden inside a wall or floor.

A sewage smell that appears only sometimes often means a small leak that dries out between uses. For example, a cracked pipe under a slab or behind a wall can release gas when water flows through it. The odor may vanish when the water stops. This type of leak is tricky because you don't see water, just smell gas.

Check areas where plumbing runs through walls, like behind dishwashers, washing machines, and sinks. Feel for dampness on drywall or baseboards. If you find any, dry it immediately to prevent mold. If you can't locate the source, a professional with moisture detection tools can find hidden leaks without tearing things apart.

You can reduce the chance of sewage smells by keeping drains and vents clear. Pour water into floor drains and unused sinks every month. Avoid pouring grease or heavy debris down drains. Have your plumbing inspected regularly, especially if you live in an older home. In Mesa, homes with slab foundations may have hidden pipe issues.

Keep the area around your main shutoff valve accessible, as you may need to turn it off quickly if a leak occurs. If you live in Mesa, write down the location of your shutoff valve and keep it clear. Regular maintenance helps you catch small problems before they become big ones. If you notice a recurring odor, don't ignore it; it likely won't go away on its own.