Sunday, October 2, 2022


“Dew” away with mildew!

By Chris Dougherty
Chris Dougherty is a certified RV technician. Here is a letter he received from a reader while he was serving as’s technical editor.

Dear Chris,
We live in Florida, where high humidity is always present. We own a 25-foot Hi-Lo trailer that I try to keep lowered and covered during the winter months. We use a Damp Rid Large Room dehumidifier and run a 12-volt fan to circulate the air. Even with all this we still have musty smells when I check the condition of the Damp Rid container. I’ve had to remove the ADCO cover and raise the trailer to try and improve the inside condition. Any ideas? —George
P.S. Great site, enjoy every issue.

Dear George,
First, thank you for the compliment! We are working hard to bring everyone the best information we can!

Florida is a tough environment when it comes to humidity and mildew. Once mildew sets in it’s hard to get rid of.

Here are a few thoughts. First, I always look at soft goods like carpeting. Any of those will hold it, as will wood products. Have you had any leaks in the unit? Concealed moisture breeds mildew, and it can grow in the wood underneath the linoleum, or in the walls or ceiling. Check the outside seals carefully, and check for any rot on interior panels and surfaces. If you can’t find any rot, I would open the unit up and remove everything (on a nice day or two of course) and spray every surface of the inside of the unit with a mildew removing solution, like a bleach and water mix in a spray bottle — just be careful about sensitive dyes and fabrics.

Lastly, keeping the unit closed up may be a contributor if the damp air is stagnant. I would consider some type of forced air ventilation that brings fresh air in and pushes old air out. I’m not certain that the chemical dehumidifier is of adequate strength to combat tropical moisture like this.

Practical Sailor did a test on a number of cleaners and mildew removers. Of the products they tested which I use every day, and did during most of my 23 years in emergency services, is Spray Nine. Home Depot and Lowe’s both sell it, and according to Practical Sailor, it is also good at removing mildew. -CD

Editor’s Note: Spray Nine products are available at Amazon.

##RVT832 ##RVDT1419


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4 years ago

We live in Florida and I bought a dehumidifier that is for a house and put in our 33 ft mh. It’s amazing the amount of water its pulling out. This works so much better than damp rid and no musty odors.

4 years ago

If you have shore power, purchase a dehumidifier. They function much like an air conditioner. When you run your A/C, it drips water outside the RV that condensed on the coils. The dehumidifier condenses the damp inside air into water which then drips into a tank. They usually provide for continuously draining the tank as well as a float switch to turn it off when the tank is full. We are in the Pacific NW and musty odors are common after months of storage. We’re always amazed by several gallons of water our dehumidifier removes even though our RV is stored under cover and there is no perceptible dampness in the upholstery or carpets.

John Mitchell
2 years ago
Reply to  Alex

I also live up in the Pacific North West – British Columbia. – I have had good luck by leaving some windows and vents open. One time I went out to my coach in January (-30) and found Hor frost all over my ceiling. I was in a panic in what to do. I left it and it was gone the next day with no water marks etc..

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