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Best Ways to Reduce Bathroom Moisture | A Complete Guide

Too much moisture in the bathroom can make taking a shower feel like a chore. The feeling of heavy mist in the air is uncomfortable and can lead to the buildup of mold and mildew. It makes cleaning the bathroom harder, especially if there is added buildup of dirt and slimy grime from humidity that has nowhere to go.

Bathroom moisture can be reduced by using a ventilation fan or keeping the window open while showering. If bathroom moisture is causing problems like water damage, mold, and mildew you may need to do more and invest in a high-quality dehumidifier or consider windows and mirrors with warm edge technology.

Read on to find out everything you need to know about how to reduce bathroom moisture and prevent long-term water and moisture damage.   

Humidity and Moisture in Your Home

One of the most important aspects of construction when it comes to bathrooms is figuring out how to provide adequate air supply and ventilation —  and this is no easy task.


There are quite a few variables at play, including different climates, as well as the placement of the bathroom. 

All of that moisture from tubs, sinks, and showers permeates surfaces and walls, and unless there is a proper outlet for evaporation and airflow, serious water damage and other issues are inevitable.

And, it’s not only your bathroom that can harbor excessive moisture — the same issues can be at play in both kitchens and basements as well. Still, the bathroom is often the toughest spot to control. 

Bathrooms are small and often closed off with one or no windows.

The problem, though, is that nearly all homeowners would agree that air-sealed walls and high-quality, airtight windows are beneficial for a multitude of reasons, including saving energy — and thus, money — and staying warm during the cold winter months. 

But for bathrooms, an airtight wall means that each time you shower, that moisture gets trapped in the wall without a way to evaporate and dry out.

And with no way for water to evaporate, it will sink into the wall, condense, and create layers of moisture, leading to mold growth, ruined or falling out tiles, damaged walls (source), and unsightly yellow stains.  

So, the question remains: how do you go about reducing moisture without having to rebuild your bathroom — or your whole home layout for that matter? 

There are essentially a few basic ways to go about doing so.

The first is to find a way to eliminate moisture altogether. The second is to provide adequate, high-quality ventilation, which can be achieved in multiple ways.  And the third is to work to clear the air of moisture as it begins to build up. 

Clearly, the first option isn’t much of an option at all for bathrooms because moisture is inevitable — unless we avoid showering, which, of course, is not something most of us would agree to do.

With the first option negated, we are left with figuring out a way to both provide proper ventilation to avoid the inevitable challenges that come with water and humidity and utilize added measures to help clear the air of excess moisture as it occurs. 

Wet blue floor tiles

Expelling Moisture from Your Bathroom

Earlier, we talked a bit about the placement of your bathroom in your home. But where your shower and bathtub are located in your bathroom matters, too. 

During winter months a poorly insulated exterior wall that is adjacent to a shower can make it easier for mold to grow. As the wall is colder and water settles in the grout between tiles, it can stay there long enough for mold and mildew to build up. 

And, while you may not immediately be able to see that buildup, the moisture behind the tiles can damage the exterior walls of your home over time. Better placement and construction planning ideally puts your shower on an interior wall to avoid this problem, but this is not always possible.

Whether your shower is on an internal wall or an external one, proper ventilation is key to prevent mold growth, and ventilation is the first step in ridding excessive moisture from your bathroom.

The Importance of Ventilation in Moist and Humid Environments

Without ventilation, humidity sits in the air and finally settles on the walls and ceiling of your bathroom. Ventilation not only reduces humidity but also prevents damage and other health issues that could arise from a lack of ventilated air, including those sourced from mold and mildew. 

Mold and mildew can create pretty big problems, and they tend to thrive in moist environments, making your bathroom an especially suitable home for both. Both mold and mildew grow pretty quickly, in as little as 24 to 48 hours to be exact (source).   

If you do find visible mold in your bathroom, the first step is to clean it well before taking measures to reduce moisture. There are quite a few cleaners on the market that will tackle mold, including bleach. 

Be careful if you are using bleach, however, especially if you have colored grout because the bleach will cause it to fade. Bleach is not effective for removing mold from porous surfaces, as it is unable to penetrate beneath the surface. (source)

Woman wearing yellow gloves holding a bleach in the bathroom

For many, bleach is not the first choice as it can be irritating to the skin and eyes, and has a few health concerns of its own. A more natural solution to clean mold is a simple distilled vinegar solution. In my article about preventing mold, I have written up a quick guide on how to clean mold with vinegar.

Clorox Clean-Up CloroxPro Disinfectant Cleaner with Bleach Spray, 32 Ounces (35417) Package May Vary

One quick note about bathroom walls that you may want to consider, especially if you have an older bathroom, is the use of wallpaper.

Unfortunately, wallpaper can make things a lot worse when it comes to bathroom moisture because mold will actually feed off of the paper (source).

If you do notice mold on your wallpaper, things can get a bit trickier, a white vinegar solution with water will work for smaller spots.

If the damage is spread over a larger area it is advisable to remove the wallpaper altogether to both reduce moisture absorption and ensure that you’ve tackled any mold growth that may occur underneath.

Bathroom Ventilation Fans

In simple terms, a ventilation fan is a mechanical device that draws out humid air, along with impurities and other contaminants that may be in the air as well.

One of the major issues when it comes to proper ventilation is that many newer bathrooms are not simply small secluded spots to wash away yesterday’s dirt and grime.

They are often elaborate, beautifully built luxurious sanctuaries where many of us spend much more time than we may realize — whether that be soaking in a tub with a good book, or just looking for a bit of peace and quiet in the shower. 

Here I have a list of 8 super quiet bathroom fans. They are truly the quietest on the market today and I will keep this list updated.

And, the more time we spend creating moisture, the more likely it is to build up.

Some of these larger bathrooms also have separate tubs and showers, and potentially double sinks as well, all of which are sources of moisture.

In large bathrooms, a small, cheap exhaust fan isn’t going to provide adequate ventilation to expel humidity and prevent water damage and mold growth. And yet, many newer homes are installed with insufficient ventilation (source).

In large bathrooms, a small, cheap exhaust fan isn’t going to provide adequate ventilation

Conversely, in older homes, there may not be any ventilation installed at all. If that is the case, installing an exhaust fan is the first step. Start by looking at a Panasonic bathroom fan, they are currently the best manufacturer on the market.

Determining the Correct Size Ventilation Fan for Your Bathroom

To determine whether or not you do have adequate ventilation, using a simple mathematical equation will do the trick. You will need to determine the square footage of your bathroom first.

For example, if you have a bathroom that is ten feet (length) by ten feet (width), your square footage is going to be one hundred.   

That number is important because when it comes to purchasing the correct size exhaust or a ventilation fan, the number you are looking for is going to be based on the amount of air that the fan is able to move out of a room, and the square footage of your bathroom.


Fans are sold in terms of their “CFM” or “cubic feet per minute.” The general rule of thumb is to purchase a fan that is 1 CFM per square foot of your bathroom (source). 

So, if your bathroom is 100 square feet, the absolute minimum number CFM that you are looking for is also 100.

If your bathroom is 100 square feet, the absolute minimum CFM that you are looking for is also 100.

It is better to overestimate rather than underestimate that number. Going a bit over is going to ensure that you have proper ventilation and have accounted for any additional space.

With that in mind, if your square footage, again, is 100, aim for a minimum 110 CFM fan.

Finally, when it comes to a properly-sized ventilation fan, a bigger bathroom may require an additional or localized fan in more than one area of your bathroom. In this case, you want to look at each fixture in your bathroom to get a good sense of the ventilation you need (source).

You can either put in a localized fan over your shower and tub, for instance or a larger, more adequate fan that will properly ventilate the bathroom as a whole. Just remember that more is better here, and if you do have a large, luxurious bathroom, multiple fans may be a better way to go. 

Bathroom SizeMinimum Ventilation and CFM Required
Less than 50 square feet50 CFM
Anywhere from 50-100 square feet1 CFM per square foot, plus 10 for unaccounted space
Larger than 100 square feet50 CFM per Toilet
50 CFM per Sink
50 CFM per Shower
50 CFM per Bathtub
(For example, if you have 1 shower, 1 toilet, and 1 sink. 50+50+50) You would need a 150 CFM fan.

Once you have the ventilation puzzle figured out and have installed or reinstalled the proper size and type of fan, you should see pretty immediate results and a reduction of humidity and moisture. 

For added measure, to double-check that your fan is working optimally to reduce moisture as well as it should, you can turn on your shower and fan and leave both running for a few minutes.

If your bathroom mirror is pretty fogged over, your fan may not be working as well as it should, and you’ll need to potentially get a new one, have it cleaned, or look into adding additional ventilation. 

There are more ways to reduce that moisture outside of ventilation fans, including the use of a dehumidifier. 

Expelling Moisture via a High-Quality Dehumidifier

AUZKIN Dehumidifier 2200 Cubic Feet (215 sq ft) Small Dehumidifier Portable and Quiet Dehumidifiers for Basements, Home, Bedroom, Bathroom, Garage, Wardrobe, RV

In addition to a ventilation fan, a dehumidifier will also work to expel excess moisture from your bathroom. Many of us have heard of or even have a dehumidifier on hand.  


They primarily work to collect excess moisture from the air, holding that moisture in a removable tank that you can then empty (source). Collecting the excess moisture will help to prevent mold and bacteria growth too.  

With a dehumidifier, the moisture is condensed over cool coils, and drier air is then pushed back into the room.

With a dehumidifier, the moisture is condensed over cool coils, and drier air is then pushed back into the room.

It does not provide ventilation in the way that a fan does, but it will certainly reduce the level of moisture and humidity in your bathroom.  

Your goal is to keep humidity levels below 50%, and the best dehumidifier for your bathroom is going to depend on the size of your bathroom and a few other specifications that may be more personal preference, including price and noise level (source)

The main factor that you will need to look at is the capacity (pints/day) in relation to the size of your bathroom.

Essentially, you want to know how much water the dehumidifier is going to be able to collect within a 24 hour period, and if it is enough for the level of moisture or humidity you are experiencing. 

Smallest dehumidifiers have a 0.45-pint capacity and will work when you have only minor humidity problems. Some more expensive dehumidifiers can cover up to 200 square feet and collect 20 pints of water per day.

When using a dehumidifier and ventilation fan, you will be able to see a difference in both the quality of air as well as the level of humidity.

One other aspect of all that moisture in your bathroom that you’ve likely noticed is the condensation that inevitably forms on windows and mirrors as you shower. 

Condensation is part of the puzzle to reducing moisture in your bathroom, and it’s the next thing you’ll want to tackle. 

Ridding your Bathroom of Condensation

Condensation is essentially all of the water droplets that form on surfaces. There’s a bit of physics involved in that when the warm moisture in your bathroom meets cooler surfaces such as walls, mirrors, and windows, the vapors will then turn to water droplets.

If you’ve ever taken a can of soda out of the refrigerator on a hot summer day, you’ll notice a lot of moisture and condensation appear there as well. The reason is that your very cold can of soda is met with very warm, humid, moist air. 

Cold soda can with moisture

The moisture in the air, when it hits that cold surface, turns to water. The same happens in your bathroom. 

Condensation, like other degrees of moisture, is the perfect breeding spot for mold growth, so it is not something to ignore. And, a lot of condensation left on walls can damage paint surfaces too.

While you cannot necessarily get rid of condensation altogether, there are ways to reduce it. 

The easiest way is to turn on your ventilation fan and dehumidifier, both of which will help. Another option is to open the bathroom door when showering if you can, this will aid in air movement.

A more complicated fix that will require significant investment is considering windows with warm edge technology, and mirrors that can be heated to keep the surface warm and reduce condensation. 

But, before we talk more about those two options, below are some simple tips and tricks that will also help (source).

  • Reduce the amount of time you are in the bath or shower.
  • Wipe down shower doors, mirrors, fixtures, and other surfaces.
  • Take a cooler shower, but turn up the thermostat to 70 degrees.
  • Be sure that your vents are open so that air can move in and out.
  • Air out damp towels and bathroom mats outside of the bathroom.

If the above solutions aren’t quite providing you with the results you want, the next step is to consider mirrors, windows, and even a floor with technology that will keep those surfaces warm and reduce condensation.

There are mirrors available that have what are called “demister” pads, which are essentially heating pads on the reverse side.

B&C 72x30 Inch LED Lighted Bathroom Mirror with Touch Button for Color Temperature, Brightness&Defogger, Memory Dimming Function, Anti-Fog Ultra-Thin Wall Mounted Mirror, Vertical/Horizontal

They will keep your mirror warm as you shower so that when the moisture in the air comes into contact with the mirror surface, it will stay clear of condensation.

When it comes to windows, some newer, more innovative, high-quality windows come with warm edge technology.

In simple terms, warm edge technology refers to a window that is constructed with multiple layers of glaze, rather than one layer in older, more traditional windows. 

As a result, these windows conduct less heat as well as lower variations in cold, resulting in lower levels of condensation (source). 

One more way to reduce condensation is to consider repainting your bathroom with a special type of paint that is designed to deflect water.

In essence, the water does not stay on the surface of walls as readily, reducing condensation, and thus reducing potential paint damage.

Once you’ve worked through your ventilation, considered a dehumidifier, and learned about ways in which to reduce condensation, you should see a noticeable difference in the level of moisture in your bathroom. 

Next, we’ll talk about a unique product called a moisture absorber. While less effective than what we’ve previously discussed, they may prove useful in some ways. 

Bathroom Moisture Absorbers

Thus far, we’ve talked a lot about moisture and how to reduce it with adequate ventilation, dehumidifiers, and even advanced warming technology. 

In addition to these solutions, there are also products on the market called moisture absorbers, many of which you can purchase, and a few that you can actually make yourself. 

Bathroom absorber gels inside a bag

Depending on the type of moisture absorber you are looking at, however, you’ll want to be careful with these around pets and children.

Essentially, a moisture absorber is defined by its name — it is simply a compound that absorbs moisture. There are various types, and you’ve probably seen a simple version inside of your most recent pair of brand-new shoes or amazon package. 

Their effectiveness is limited in the bathroom due to the high humidity levels, but it an be a good temporary or contributing measure to controlling moisture in the bathroom.

Silica Gel and Calcium Chloride

Both silica gel and calcium chloride work to remove moisture from the air through a process called “adsorption.”

In the simplest of terms, adsorption simply refers to the process in which liquid molecules adhere to the surface of a solid, or adsorbent, removing moisture from the air (source). 

Those tiny little packets you see inside new shoes or in packaging material work to keep moisture at bay, but you’ll also often see “Do Not Eat” written on those bags as they can be dangerous if ingested. 

Desiccant silica gel pack

Some moisture-absorbing products contain silica gel, rock salts, or calcium chloride, as do some dehumidifiers, for the simple reason that they do work well to reduce and remove moisture from the air. 

In general, these products, in and of themselves, are not recommended for large rooms such as your bathroom.

An exception would be if used as part of your dehumidifier or another product that uses these compounds as part of a container that, in effect, collects moisture from the surrounding area. 

Clay Absorbers

Clay is another way in which to absorb moisture from the air, though its effectiveness is quite a bit lower than other methods. 

The use of clay is relatively inexpensive, less toxic than some other moisture-absorbing options, and can reduce the level of dampness in a small area.

Still, for very humid locations such as a bathroom, it is not going to get the job done quite as well as you need. 

So, essentially, moisture absorbers do indeed work. Whether they will work well enough for the size and humidity level of your bathroom is debatable.  

One place that they do work well in a bathroom is on windowsills, especially if your windows are older or wooden.

You can set a moisture absorber on the window sill, and it will help to keep the small area around your windows drier, with less condensation buildup as well.

Tackling Drafts to Help Reduce Moisture

It almost seems counterintuitive that an unsealed draft in your bathroom can lead to added moisture buildup, but it could be part of the problem. 

When we are talking about drafts in the case of bathroom moisture, we are mostly addressing leaks that allow moist air to enter into the walls and ceiling.

When this happens, that moist air will enter into those areas and potentially cause damage. These are not necessarily do-it-yourself, fix-it problems, but ones that you may need to address with a professional. 

So, if you notice mold forming in the attic above the bathroom, there is a good chance that the moisture from the bathroom is leaking into the cold attic.

Final Thoughts

Excessive moisture in bathrooms, basements, and kitchens is a very common problem with bathrooms being one of the worst. 

Still, there are ways to reduce all of that moisture. These might be simple steps like remembering to turn on the bathroom fan, keeping windows open, taking shorter showers and hanging towels elsewhere to dry.

More significant investments would include a high-quality dehumidifier, adding additional ventilation fans, or investing in warm edge technology windows.

Start small first. You may be surprised as you discover that the simplest of steps will help to reduce discomfort and damage before you need to look into bigger, more extensive solutions. 

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