Does Putting a Damp Sponge on a Radiator Improve Humidity? Experts Weigh In

With the heat cranked up and the air noticeably drier, chapped lips and scratchy throats are sure to follow. Many of us look for a quick fix, which likely explains why the "damp sponge on a radiator" trick has garnered traction. But does it actually work?

To find out, we asked HVAC experts to weigh in—and what you may want to try instead if you're looking to improve your home's humidity.

Can a Sponge on a Radiator Humidify a Room?

Unfortunately, putting a damp sponge on your radiator will not make any sizable difference in your home’s humidity. While heat may cause a small amount of water in the sponge to evaporate, the moisture released is minimal and won’t meaningfully raise a room's humidity. Not only is it ineffective, but it can also be dangerous. “It can actually lead to mold issues and damage to your radiator,” Dale Chason, HVAC Manager at Awesome Home Services, shares. 

This is especially of concern if there are curtains or other nearby porous fabrics or surfaces, explains Rick Hoskins, HVAC, air quality, and filter expert at FilterKing. “As the water is released from the sponge, it can make the curtains damp and eventually cause mold growth,” says Hoskins.

Besides mold, there’s also a risk of fire, depending on the radiator unit you have. “It can be dangerous to use the wet sponge method on an electric baseboard radiator,” Hoskins warns. “Electric radiators get much hotter than older styles, so there’s a small risk that a wet towel or sponge could catch fire if left on the radiator for too long. And of course, electricity and water don’t mix.”

6 Alternative Options for Improving Humidity Levels

Turns outs, this old-school trick is more of a myth than an effective solution to your dry-room woes. Our experts share six alternatives for more effective (and safer) ways to improve the humidity in your space.

• Add a whole-home humidifier to your HVAC system. As Chason explains, these will "distribute moisture evenly through the ductwork, maintain consistent humidity, and limit physical issues like dry skin, static, and respiratory irritation."
• Leave your bathroom door open after a shower. Hot showers equal steam, and you can use the humidity to your advantage. Turn the exhaust fan off after a shower (and leave the door open) to let the steam circulate your space.
• Grab a portable humidifier. “I recommend looking for units sized appropriately for your room and cleaning them regularly to prevent bacteria or mineral buildup,” Chason says. “Evaporative models are safer because they self-regulate output better than ultrasonic units.”
• Add house plants. Plants naturally help with humidity through a process called transpiration, which is when water vapor is released through the plant’s leaves.
• Air-dry your laundry inside. Drying your clothes on a rack indoors gradually adds moisture to the air as your damp clothes dry. Not only are you saving energy by not using your dryer, but you’re also increasing the home’s humidity. That’s a win-win.  
• Run your kettle. Boiling water on the stove naturally releases steam into the air, which can add humidity to the room the kettle is in.