Why Is There Mold Under My Kitchen Sink?

The most common reason is a slow leak. A loose supply line, a worn washer, or a cracked drain pipe can release tiny amounts of water every time you use the sink. That moisture seeps into the cabinet base, and the wood stays damp for hours or days.

High humidity also plays a role. Warm, humid air from washing dishes or running the dishwasher can condense on cold pipes and cabinet surfaces. If the cabinet has little airflow, that moisture lingers. In humid climates, summer humidity can make the problem worse.

Once you stop the leak, remove everything from the cabinet. Wipe down all surfaces with a mild detergent and water. Then dry the area completely with fans or a dehumidifier. Mold can return if any moisture remains.

For porous wood that is already stained, you may need to remove and replace it. Water-damaged flooring or cabinet bases can hold mold spores even after cleaning. If the mold covers a large area or you smell a musty odor, consider structural drying and dehumidification to pull moisture out of the wood.

If the mold covers more than a few square feet, or if you see mold on drywall or the subfloor, you may need professional help. Mold can spread behind the cabinet and into the wall cavity. The pros can assess the extent of the damage and remove water-affected materials safely.

They also have equipment to dry the structure thoroughly. In a humid climate, drying is essential to prevent mold from returning. If you are unsure about the source of the leak, a professional inspection can identify the problem and help you decide on the next steps.