Why Use A Dehumidifier In An RV?

Humidity buildup can be a problem in any vehicle and staying in a damp and sticky RV or trailer is neither comfortable nor healthy. There are a few ways to control the humidity level in your camper but a dehumidifier is the best and easiest option to stop the windows from fogging up.

A dehumidifier is essential in protecting your RV. Even when it’s parked and closed up, moisture can collect on hard surfaces, be absorbed into upholstery, and cause extensive and expensive-to-repair damage. If you’re occupying the space with pets and family, it’s even more important to extract the extra moisture from the indoor air.

There is a wide range of dehumidifiers to choose from, but before you do so, let’s look at some detail into why you need one, exactly what it needs to achieve for you, what types of dehumidifiers are available, and which are recommended for your particular needs.

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Reasons Why You Should Use A Dehumidifier In Your RV

If you have had a full day of outdoor activity, the last thing you need is to return to your mobile home and find that it’s uncomfortably hot and humid, and opening all the windows and vents doesn’t make much of a difference.

A dehumidifier, programmed to switch on a few hours before your return, is the only effective way to ensure a cool, comfortable environment in which to truly relax. 

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Warning Signs Of Excess Humidity In Your RV

It may be a while before the visible signs of damage can be seen. Your RV will be more susceptible to this damage in humid coastal areas than in cool, dry mountainous regions, but be on the lookout for:

  • Stains and discoloration on walls and ceilings are caused by moisture absorption into the materials.
  • Visible mold and mildew in enclosed areas such as cupboards, showers, or fridges are areas where ventilation is limited. High humidity levels create an ideal atmosphere for unsightly and unhealthy organisms, which can even affect your health.
  • Condensation and build-up of moisture on windows, caused by the cold external temperatures and the warm air inside your RV.
  • Damp, musty smell – in confined spaces smells are concentrated, and high humidity adds to the problem causing a musty smell.

Check out my recent post about improving the air quality in your RV or trailer

Choosing A Dehumidifier For Your RV

The size of dehumidifier needed to regulate the moisture of the air inside your motorhome or trailer will be determined by the interior square footage of your unit, the number of rooms and how the space is broken up.

Most RVers will get by with a small dehumidifier that can be easily stowed for travel and doesn’t take up much floor space. If your rig has multiple rooms with doors that are kept closed you may want to consider having a second dehumidifier to use while sleeping in the bedrooms.

Having an air purifier will help remove pet dander, generator fumes and outdoor allergens while you’re out enjoying the wilderness in your camper or trailer. My latest article on the best air purifiers for an RV for more info.

Regulating The Humidity In Your RV

Many versions of dehumidifiers have a built-in meter that measures the humidity in the immediate area and can be set to the required level (rather like a thermostat on a heater).

Ideally, the humidity levels should be between 30% and 50%, and if your dehumidifier is not self-regulating, you can install a wi-fi humidity monitor or a digital hygrometer that will warn you of any increase in humidity above acceptable levels.

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Factors To Consider When Buying A Dehumidifier

Like any device in the home, your RV dehumidifier must offer the best possible solution in terms of its cost-effectiveness. 

The smaller units may not be powerful enough to dehumidify efficiently, while the largest may be unwieldy and impractical in the confined space of your mobile home. Some factors for you to consider include:

  • Portability: Many humidifiers have castors and handles which allow you to move it easily from one section of your RV to another and even to remove it when not in use
  • Operational noise:  If you’re spending time in the limited space inside your RV, the noise factor is important, and there is quite a difference between the various models, so make sure you’re comfortable with this aspect.
  • Ease of operation: If you spend a large part of your day away from your mobile home, it’s a major plus factor to have your dehumidifier programmable so that it turns on and off automatically and allows you the luxury of returning to a cool, fresh and dehumidified camper. 
  • The external weather conditions: If you’re going to be using your RV in a location where the climate is humid and warm, it’s going to take a high-capacity dehumidifier to ensure your comfort inside. Conversely, there’s less need for a large humidifier if you’re located in a cool, relatively dry environment.
  • Internal conditions:  Your choice of dehumidifier depends on how many people will be living in the RV and how much time they will spend in the vehicle. Activities such as cooking and taking hot showers will significantly impact the humidity levels inside. 

Additional Ways Of Reducing Humidity In Your RV

Nothing you can do will replace the function and effectiveness of a dehumidifier, but you can increase that effectiveness by taking preventive measures to reduce the build-up of excess moisture: 

  • Open windows and vents when appropriate to allow air to circulate
  • Wipe down surfaces regularly to remove moisture
  • When possible, cook outside of your RV to reduce heat and moisture levels
  • Check for leaks in the roof and sidewalls of your vehicle
  • Use moisture-absorbing pellets such as DampRid in small, confined areas such as cupboards and closets as a supplementary means of reducing humidity. 

Check out this checklist and guide to inspecting your RV or trailer for water damage

What Type Of Dehumidifier Is Used In An RV

There are essentially two types of dehumidifiers that can be effective in your RV: refrigerant and desiccant. Each type uses different methods to achieve the goal.

The refrigerant dehumidifier works by drawing in the air using a fan and then passing this air over refrigerated coils. Water then condenses into droplets on the coils and is stored in a tank in the dehumidifier for later disposal. 

The desiccant type operates in much the same way, but instead of coils, the air is drawn in and passed through moisture-absorbing pellets or silica gel in a large rotating wheel to reduce humidity levels. An electric fan then delivers the cooler, drier air back into the living space.

Refrigerant dehumidifiers are, generally speaking, heavier than desiccant models and also tend to be a little noisier. However, they are cheaper both in terms of their initial and long-term running costs and are far more effective in dehumidifying larger areas. 


Your RV is either your home or your vacation accommodation – either way, it’s not an expensive asset, but it enables you and your loved ones to visit various parts of this beautiful land in comfort and style. However, living in a confined space with high humidity levels can be unpleasant and unhealthy. 

There are no effective alternatives to dehumidifiers, and there are so many to choose from that there will certainly be one that offers you the perfect product in terms of convenience, performance, and affordability. Once you have one installed in your RV, you’re assured of a level of comfort that will never again dampen your spirits!


Beau is an electrical engineer with a knack for DIY repair and construction. When he's not tinkering with his projects he's on the road travelling and enjoying an exciting lifestyle with his young family.

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