Moisture in air ducts is never a good sign, as it can promote the growth of harmful bacteria and fungi. Moisture can be caused by the HVAC system itself, the absence of a humidifier or by other elements, such as leaky pipes or leaks in your roof.

According to Jenkins Restorations, condensation on or near cooling coils of cooling systems is a major contributor to moisture in ducts. Condensation is something that occurs naturally and is produced when the temperature of air in the HVAC system is below the temperature of surrounding air.

While some more advanced ductwork systems have technology in place to extract moisture without spoiling ductwork, there are many HVAC systems in commercial and residential use that don’t have such a feature. Applying insulation to ductwork in areas that aren’t cooled, like unfinished attics, is vital to minimizing moisture, but once it’s in there, long exposure to air and the right insulated conditions is the only way to get rid of it. 

As for the mold that grows along with the presence of moisture, companies like Foster-Fuller provide EPA-approved mold killing products and inhibitors for use after cleaning. For the cleaning step of the process, on non-porous surfaces (such as steel ductwork and vent covers), you can use 1 part bleach with 16 parts water.

What do I do if I get water in floor air vents?

If you notice water in any vent, it is important to examine all other boots and ducts for a possible source for the water. After examining all possible sources for water, if only one vent has been discovered with trouble, then first eliminate possibilities such as over-watering houseplants or a nearby water spilling. If you cannot find anything, make note of weather conditions at time of occurrence and which vent it is, and keep an eye on the water to see if it stays in the vent, or comes and goes. Then, call a HVAC and ductwork professional.

Why do I hear water running in my air conditioner?

You may hear the repetitive sound of dripping water coming from your indoor air conditioner unit.  More than likely, this can mean that the condensation is not draining properly.

Next steps

Taking the necessary steps to prevent water buildup in ducts can save you hundreds – even thousands – of dollars and create a safe and comfortable space to live. While it may seem easier to clean out your own air ducts, it is best to contact a professional to get more information and make sure things are done properly.