Bleach and dry storage beat vinegar every time

Bleach is the answer, and a thorough dry-out is the prevention. Vinegar won’t reliably kill mold on the porous plastic inside a cooler.

Start by washing the whole interior with warm water and dish soap. Then mix about one tablespoon of bleach into a quart of water, wipe down every surface, and let it sit for 5–10 minutes. Scrub the moldy spots with a soft brush or sponge, rinse with plain water a few times, and dry it completely — and I mean completely. Leave the drain open, prop the lid up, and let it air out for a day before storing.

Mold comes back because coolers are damp, dark, and warm — basically a mold spa. So the trick is to remove the damp. Store the cooler with the lid cracked or slightly open, not sealed shut. Keep it in a dry place. If you live somewhere humid, toss a desiccant pack or a small box of baking soda inside. And never put it away wet, even if it’s just from melted ice.

Future beer tastes much better coming out of a clean, dry cooler.