Humidifiers require regular cleaning. The more you use yours, the more vigilant you must be. That’s because mold can grow within 48 hours on wet surfaces, and mold in the tank or in the water can then be transferred into the air, potentially causing itchy eyes and breathing troubles.

Even units with antimicrobial finishes on tanks and wicks will become scaly and moldy if they’re not cleaned. Some manufacturers claim that adding bacteriostatic solutions to water will slow bacteria growth. We didn’t test this claim. For the best results, follow these tips:

Change the water daily. Empty the tank, dry all interior surfaces, and refill with clean water.

Clean your humidifier often. Although some parts may be washable in the dishwasher, they still need to be descaled with vinegar and disinfected with bleach. Completely dry all parts between descaling and disinfecting. And after disinfecting, carefully rinse the tank to avoid breathing harmful chemicals. Follow the manufacturer’s directions and schedule for descaling and disinfecting parts and replacing filters, wicks, and the like.

Clean it before you store it. And clean it again when you take it out of storage for the heating season.