5 Steps to Remove Mildew Smell From a Cooler

Wash with dish soap Scrub every surface with warm water and dish soap, including the lid and drain plug. Rinse thoroughly.

Apply baking soda paste Mix baking soda with a little water to form a paste and spread it inside. Let it sit for 15–20 minutes, then scrub and rinse.

Use vinegar solution Spray or wipe a 50/50 mix of white vinegar and water inside. Let it sit for 10 minutes, then rinse thoroughly. The vinegar neutralizes the baking soda and kills the mildew smell.

Air dry completely Leave the cooler open with the lid and drain open for at least 24 hours. Never close a damp cooler—mildew loves moisture.

Try bleach as a last resort If the smell lingers, use a diluted bleach solution (1 tablespoon per gallon of water). Be careful: bleach can discolor plastic and leave a chemical smell, so rinse multiple times.