Why Does My House Smell Like Rotten Eggs After Rain?

Rain can drive water into parts of your home that usually stay dry, like crawl spaces, basements, or under sinks. That moisture can feed bacteria that produce hydrogen sulfide, which smells like rotten eggs. Another common source is sewer gas leaking from a dried-out floor drain or a cracked pipe.

If you have a private well, heavy rain can stir up sulfur bacteria in the groundwater. The smell may show up in your taps or washing machine. In Bellingham, the wet season can make these issues more noticeable.

• Dried-out floor drains in basements or laundry rooms
• Cracked or loose sewer pipes under the slab
• Sulfur bacteria in well water after heavy rain
• Standing water in crawl spaces or attics
• Clogged or backed-up drainage lines

Rain can seep through foundation cracks, window wells, or roof leaks, leaving moisture that fosters mold and bacteria. A musty or rotten egg odor often appears after the rain soaks into hidden spaces. Inspect your basement walls, attic, and around windows for dampness or staining.

If you find wet insulation or soaked drywall, that material can hold moisture and smell for days. It may need to be removed to stop the odor. Pay special attention to areas where pipes enter the house, as gaps around them can let water in.

Keep your gutters and downspouts clear so rain flows away from the foundation. Make sure the ground slopes away from your house to prevent pooling. Seal any cracks in your foundation or around pipes to reduce water entry.

Refill floor drains with water every few months, especially in unused areas. If you have a sump pump, check that it works before the rainy season. For well water, a water treatment system can address sulfur bacteria.