How to Control Humidity in Your RV

Humidity is the measure of water vapor in the air. And high humidity in an RV can be a serious problem. Here are tips to control the humidity in your RV.

How to control humidity in your RV with a dehumidifier and other tips to maintaining the proper moisture level in an RV

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Why Humidity is a Problem

Ideal humidity is between 30% and 50% for most temperature ranges. If the humidity gets too high, you are bound to have problems.

Humidity in your RV is a problem for a variety of reasons. Whether because it is health, comfort, or maintaining your investment, maintaining proper humidity levels is necessary.

Health Concerns with High Humidity

High humidity can lead to health problems when you are in your RV.

Do you have allergies? Then you definitely want to keep humidity, and thus moisture, under control. Bacteria love to grow in moist environments. Likewise, dust mites and mold also thrive in a humid environment.

The World Health Organization cautions people that people exposed to mold “are at increased risk of respiratory symptoms, respiratory infections and exacerbation of asthma.”

High humidity can also lead to dehydration. In what seems counter-intuitive, your body will actually produce more sweat to help keep your cool. This water loss can be dangerous to your health.

Low Humidity Can Cause Health Problems Too

Did you know that low humidity can also lead to higher infection rates?

Brand new research says that the ideal humidity range is between 40 to 60% to keep our body’s defense systems working properly to stop things like flus, colds, and other infections.

See our skin dries out and flakes off, launches microbes into the air which cause infection in others. And our skin is damaged, leaving small, sometimes invisible cracks for other microbes to get in and infect us. Our skin is our biggest defense against infections and we need to protect it by keeping it properly hydrated.

High Humidity Isn’t Comfortable

You want to enjoy your RV. And high humidity makes it uncomfortable.

When the humidity gets above about 60%, you’ll notice that it feels muggy and uncomfortable. Take it from a Southern girl who deals with humidity all the time, it’s not comfortable. On the other hand, dryer air feels cooler.

One reason it isn’t comfortable is because your sweat won’t evaporate as well in high humidity. Remember how your body will sweat more and could cause dehydration? In addition to being a health concern, it also makes you uncomfortable. And excess sweat is well, gross.

At night, this excess sweat can lead to sleeping problems. Tossing and turning and sweaty sheets. No thanks.

High humidity will also lead to a musty smell. It’s partly a function of mold and mildew and just a general dampness. In any case, who wants to live in a musty RV? Keep it dry!

Finally, part of the comfort of living in an RV is being able to enjoy the scenery. High humidity will lead to windows fogging or condensation forming on the windows and blocking your view. If you are driving, it can also be a safety concern.

See Also: More Tips for Reducing RV Odors

Maintain Your Investment in Your RV

Whether you spent $4,000 like I did on Starter RV or a lot more on something like a Tiffin Motorhome, you made an investment in your RV. Don’t forget about all that money you’ve spent on furnishing your RV and making it comfortable. Now, you need to maintain that investment.

High humidity can lead to problems like mold growing on your bed, on walls, and in the floor. Not only is this bad for your health, but it will lead to a drastic hit to your pocketbook.

The wood in your RV, like the subflooring, walls, and cabinets can swell, rot and deteriorate over time. Do you really want to be ripping up the carpet and the subflooring to do major repairs? Wouldn’t you rather be spending your time on the road or camping?

High humidity can also do a number on cast iron cooking pots and pans. Find out how to remove rust from your cast iron skillets.

How Humidity Builds Up In Your RV

Humidity is a function of water vapor in the air. So, all the ways that water vapor happens will cause humidity to build up in your RV.

Tasks like:

  • Cooking, especially boiling water
  • Showering
  • Breathing
  • Washing Clothes
  • Sweating

Basically, every day living will cause humidity in your RV. This is on top of the general environmental causes, like you know being in the South instead of the Southwest/desert. Or rain.

High humidity can also be a sign of leaks in your RV.

Monitor Humidity in Your RV

The first step is to know what the humidity is in your RV. The easiest way is to have a thermometer with a built-in humidity gauge. This model has high and low records so you can tell what conditions were like during the day. Because as the weather changes, so will the humidity in your RV.

Some of the RV Remote Temperature Monitors also have humidity or water sensors. The water sensors are best to monitor in case of busted pipes or the like and not necessarily the water vapor in the air.

Reduce Humidity in Your RV

Now that we know why you don’t want high humidity and that the humidity is actually high in your RV, it’s time to work on reducing the humidity. You won’t actually want to eliminate the humidity entirely because that’ll cause problems of its own.

Fix Leaks

One thing you should do immediately is fix any leaks. This isn’t just about humidity because actual standing water will do damage a lot faster than water vapor in the air. Nonetheless, the problems are the same and will lead to mold and other damage to your RV. Fixing even a small leak will help reduce the humidity in your RV by not introducing new water inside.

It’s not just roof leaks either. A small leak from your sink, toilet, or shower can cause high humidity and all the associated problems. Make sure that you fix these issues right away.

Keep Air Moving

One problem with many RVs in storage or between trips is the lack of air flow. When everything is buttoned up tight, air can’t move. This means that the humidity will build up inside the RV instead of being exchanged with dryer air outside. Also, all the mold spores, bacteria, and dust mites are stuck inside your RV if you don’t keep the air moving.

The Fantastic Vent Covers are wonderful additions because you can leave the vents open even when it is raining. Be sure to open up the vents when you are cooking or showering since those are high humidity daily living event. In addition to opening up the vents, cracking a window near your kitchen or bathroom during these high humidity events can help move the humid air outside.

Small fans also help. You can run the ones in the windshield. I also use some small USB style fans to help keep the air moving, even while the RV is plugged in during storage (so I don’t run the batteries down).

Run the Air Conditioner

The air conditioner is awesome at reducing humidity. As the AC cools the air, it also removes humidity. In addition to the cooling properties, just moving the air around will help control humidity. Make sure that you perform regular maintenance on your air conditioner so that it runs in tip-top shape.

Beware of “swamp coolers,” otherwise known as evaporative coolers. These actually put more moisture in the air! Many are even marketed as a humidifier; they definitely won’t help you keep humidity low in your RV. Moreover, these lose much of their effectiveness in higher humidity. Remember how you sweat more when the humidity is higher because your body doesn’t cool as well? Same principle at work here.

Cook Outside or Use Other Cooking Methods

Some cooking, more than others, will really affect the humidity levels. Things like boiling water for pasta, a low country boil, or ice tea should really be done outside if at all possible.

You can also use ice tea from concentrate. It’s what I use at home and in the RV – no boiling water, inside or outside, required. And it’s much better than the old sun tea stuff.

Crock-Pots and Instant Pots tend to put out less water vapor than traditional cooking methods. If possible, try opening them up outside, which also helps with the heat inside the RV during the summer.

Dry Clothes Outside

If you have a clothes washer and dryer in your RV, these things can be awesome conveniences. But they can also take up a lot of power and a lot of water and produce a lot of heat and humidity.

If you are struggling with high humidity while you are living in your RV, try using a campground or local laundromat instead of the onboard washer and dryer. One advantage is that in many of these laundromats, they have multiple high capacity washers and dryers, letting you do a bunch of laundry at one time. Another advantage is that you are not putting all that water vapor inside your RV.

If you don’t have a laundromat available, then try hanging your clothes outside to dry. Many campgrounds have restrictions on hanging clothes outside, so this might be an issue. But if you are not in a campground or your campground does not have this restriction, then drying your clothes outside can definitely help with the humidity inside the RV.

Use De-Humidifiers

If all else fails, invest in a de-humidifier.

There are two main versions of dehumidifiers that RVers use: those that require power and those that do not require power.

Powered Dehumidifier

Small yet powerful dehumidifiers are great in an RV.

Unfortunately, the smaller dehumidifiers have two small problems – they don’t have drains and they don’t have a built-in hygrometer or humidstat (to measure the humidity level).

You have to come into the RV and empty the tanks about once a week or so if it has been raining or other high humidity conditions. This is not all a bad thing since it’ll give you a chance to keep an eye on the inside for pests or bigger water leak issues.

You can also drill a small hole and then use small plastic tubing to create your own drain. Since you probably won’t need a lot, go with the aquarium tubing. It works great, is cheap, and you won’t have to store hundreds of extra feet. Add a couple of drops of silicone sealant around the tubing to keep it from leaking out of the water reservoir.

Whether you get a larger dehumidifier or use the small dehumidifier with a DIY drain, snake the tubing either out the window or into the sink or shower drain.

Humidity Monitors

Some people prefer the larger dehumidifiers that come with additional features, like programmable timers to only run when you aren’t in the RV, air filters, and built-in humidity monitor so it doesn’t run once a low humidity level has been reached.

Of course, these larger dehumidifiers come with an additional cost and take up additional space.

The smaller dehumidifiers work well when in storage and can work just as well when you are living in the RV. If you want to continue to use a smaller dehumidifier, then you should get a hygrometer to separately monitor humidity levels and then manually shut-off the dehumidifier when the level drops below 30%.

Non-Powered Dehumidifier

Not everyone has power to run a dehumidifier, especially when the RV is in storage. But don’t let this be a reason to allow high humidity in your RV. There are options to reduce humidity even when the RV is without power. Or if you are boondocking and need to conserve your RV batteries.

My favorite is the Eva Dry Renewable Dehumidifier. While it takes power to recharge, the dehumidifier functions without power from the RV or batteries and is silent. Once the crystals are full of water (you’ll know by the color of the crystals), you just plug it in to dry them out and recharge for future use. It takes 3-8 weeks for the crystals to be full of water but only 12-14 hours plugged in to dry out.

The backup is Damp Rid, which is generally not rechargeable. You can, however, get Damp Rid crystal refills to help reduce your waste and save some money. Damp Rid sits in small buckets and absorbs water moisture in your RV. The smaller, hanging Damp Rid bags are good for extra moisture absorption in your RV closet, under the bed, or other small spaces where air flow is more restricted.

In Conclusion: Control Humidity in Your RV

Tips for controlling the humidity in your RV including using a dehumidifier but also other tips. Find out why high humidity is bad for your health, your comfort, and your investment in your RVHigh humidity in your RV is bound to lead to problems for your health, your comfort, and your investment in your RV. As a result, you should monitor the humidity levels and take action if the relative humidity goes above 50%. You can reduce the humidity in your RV reducing activities that cause higher humidity in the RV, by using proper ventilation to move humid air out of the RV, and using the air conditioner or a dehumidifier to remove water vapor from the air.

If you are going to use a dehumidifier, then RV Tailgate Life recommends small yet powerful dehumidifiers when you have access to power. If you do not have a regular power source, then the Eva Dry Renewable Dehumidifier is a useful alternative.

Don’t forget to get a hygrometer so you can monitor the humidity lvels in the RV! Remember, the ideal range is about 30-50 or 40-60% humidity.

Not too high, not too low.

Just right.

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  1. I’m very puzzled with the interior “Rain” I continue to fight in my 5th Wheel. I have an 1100sq foot dehumidifier inside my 200ft 5th wheel. I also have 6 hanging and 2 sitting Damprid containers. Nothing seems to make any difference to help lower the humidity in here. My Windows, and I have 3 cracked open, are always full of steam. I have a lot of mildew on the iside edges of the windows in my bedroom. What else can I do? I’m also using an electric heater and have turned the fan on, so air is moving around. It’s 55 outside and I’m on the southern most city, on the coast, in Oregon. I’ve yet to find others, in the park, with the same problem, so apparently it’s something I”m doing wrong. I don’t boil water inside, I use a Toaster Oven and Microwave to cook in. I’m truly stumped. Any ideas would be greatly appreciated.

    1. Sheri,

      The coast of Oregon is notoriously damp/wet/humid. But you shouldn’t be having those kind of issues.

      My recommendation is that you look to see if you have any leaks – roof, windows, side panels, etc. Since you are getting mildew around the windows, start there. I’m wondering if there are gaps or something there, allowing for excess water to come in. Also look above them – could water be running down but collecting here because of the edges of the windows? Perhaps a small leak around a seam where the roof meets the side wall.