Updated September, 2025
Brought to you by the professionals at Southport Home Services
Imagine that your reach for the thermostat to turn on the air conditioner. Punch in a few settings to set the temperature in your house exactly how you want it. Then you feel the nice crisp, cool air rush into your home. Over the next few days though, you notice there is a tinge of stink in the air. You hop on the internet and learn something surprising, there is a water pad in your humidifier that requires changing! This stink in the air could be a result of keeping the same water pad in your humidifier for multiple heating seasons. In this article, we will discuss how often your water pad needs to be changed.
To start off, let us discuss why the water pad in your humidifier needs to be changed. Throughout the heating season, there are numerous amounts of particles and bacteria flowing through the water pad. All of the bacteria and particulates get caught up in the humidifier pad and remain there on the pad. When the water pad goes multiple heating seasons without being changed, the bacteria and particulates have enough time to grow mold and other bacteria. Therefore, increasing the chances of mold and bacteria being spread throughout your house. Even when your humidifier is turned off in the summer, there still can be air flowing through it.
Now that we know why your water pad needs to be changed, let’s talk about when. If you have read our When to Change a Furnace Filter article, you may be expecting an answer along the lines of ‘It depends.’ Since a water pad has a similar function as an air filter, you would think this would be true. In fact, with a water pad, this is not true. There is a more definitive answer when it comes to water pads. A water pad should, on average, be changed once every heating season. There is not much difference to when in the season it is replaced, just that during the season you switch it out for a new one.
Don’t Forget the Humidifier Water Panel!
For homes equipped with a whole-house humidifier (often attached to the furnace plenum), changing the water panel – also called the humidifier pad or filter – is key to keeping it working effectively. Here’s what you need to know:
- Frequency of Replacement: In Wisconsin, you should generally replace the humidifier pad at least once each heating season. A good rule of thumb is to put in a fresh pad every fall. If you run your humidifier heavily or have very hard water, you might even change it mid-season (around February) to maintain output. Mineral deposits from evaporating water can clog the pad over time.
- Signs It’s Time: If you notice your humidifier isn’t maintaining humidity like it used to, or you see white crusty buildup on the pad during an inspection, it’s time for a change. Another sign is water overflowing or not draining properly from the humidifier – a clogged pad can cause misdirected water flow. Replacing the pad will restore proper wicking action so the unit can evaporate water efficiently.
- DIY vs. Professional: Replacing the water panel is a relatively simple task for handy homeowners. Make sure the furnace is off, then open the humidifier cover, slide out the old pad (beware of mineral gunk), and insert the new one following the arrows (orientation can matter for some models). If you’re not comfortable doing it or unsure which pad to buy, our technicians can service your humidifier during your annual furnace tune-up. We’ll also clean the orifice and ensure the water feed tube and drain are clear.
- Tip – Soak New Pads Briefly: Some manufacturers suggest pre-soaking a new evaporator pad in a glass of water for a minute or two before installing. This ensures it’s evenly wet from the start. Always follow your specific humidifier’s instructions, but this trick can help jump-start the evaporation process after a dry pad goes in.
Regular pad changes not only keep your humidifier’s output at peak levels but also help the unit run cleaner. A fresh pad means more moisture in your air and less strain on the system’s water supply components. Mark your calendar each season, and you’ll consistently reap the comfort benefits of your home humidifier.
Don’t think you will remember to change it next heating season? Sign up for The Southport Home Services Club today! We will send you an email and remind you each heating and cooling season when it is time for your Tune-Up, during which, any filter or water pad can be purchased from Southport Home Services.
