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Mold in RV Tanks Is Common, Here’s How to Fix It

Many people fear discovering mold in an RV tank. Mold can be dangerous, cause serious health conditions, and make your water smell. However, mold in RV tanks is more common than you think. 

If you’ve not kept up the maintenance on your RV, there’s a good chance you have mold in your tank right now. Let’s look at how you can fix it.

What Is an RV Tank?

RVs have various water storage tanks. You have freshwater tanks for storing clean, potable water and waste. RVs typically have both gray and black water tanks. Knowing the difference between the two is very important.

Gray water tanks store water that goes down a faucet or shower drain. This is primarily soapy water from taking showers, washing hands, and doing dishes. However, if your gray water tank contains too much dishwater, it can get gross and have a foul odor. 

Do RV Tanks Get Moldy? 

RVers typically expect their black RV tanks to smell because they hold raw sewage, but odors from a gray tank usually come from mold. 

Moisture inside of the tanks will sit for extended periods, and the hot and humid weather can create the perfect environment for mold and other bacteria to grow. 

Unless you stay on top of sanitizing your tanks, you likely have mold growing in them.

How Do I Get Rid of Mold in My RV Water Tank? 

The only way to get rid of mold in an RV water tank is to sanitize your entire water system properly. This can be time-consuming, but having mold-free tanks is worth your time. You’ll also use a ton of water during this process, so make sure you connect your RV to a water source and sewer connection.

First, you’ll need to use a quarter cup of household bleach for every 15 gallons in your fresh water tank. Pour the appropriate amount of bleach into your potable water hose and then connect it to your water source. 

This will then send the bleach into your fresh water tank and create the appropriate consistency. Once you’ve filled the tank, turn on every tap and shower head and flush every toilet until you can smell the bleach solution.

Give the solution time to do its job, which typically takes at least four hours. However, it’s a good idea to do this project before bed and let it sit overnight. 

You can then run the fixtures to pump all the water out of your fresh water tank and fill your waste water holding tanks. 

Finally, once you’ve drained all the water from your fresh water tank, refill it with clean water and let each of the faucets and shower heads run until you no longer smell bleach.

How Long Can You Leave Bleach Water in an RV Tank? 

The bleach water solution in your RV tank will need time to work to get the mold out. It typically takes four to eight hours. You should never let bleach water sit in your RV tank for longer than 12 hours. 

Bleach is a powerful chemical that can cause damage to the rubber seals and components in your plumbing system. Ensure the bleach/water solution isn’t too harsh for your plumbing system. 

Stick to a quarter cup for every 15 gallons, and you’ll likely experience no issues.

How Do I Sanitize My RV Water Tank Without Bleach?

Some people don’t like putting bleach into their fresh water tank. If you want to avoid harsh chemicals and still sanitize your tank, you can also use white vinegar. 

Use a 50/50 mixture of water and white vinegar and pump it into your fresh water tank before hitting the road.

As you travel, the water will slosh around in your fresh water tank and clean it. It will remove some of the mold and gunk sticking to the inside of your RV tank and will come out when you dump your tanks. 

When you arrive at your campsite, run all the faucets and fixtures in your RV until you smell the vinegar. Go out and enjoy the outdoors for a few hours. Then come back to run clean water through your entire system.

How Often Should I Clean My RV Fresh Water Tank? 

You should clean your RV’s fresh water tank at least every six months. If you’re a weekend warrior, it’s a good idea to make this a part of your routine maintenance at the beginning and end of each camping season. 

However, full-timers will need to do this more frequently to avoid mold in your RV tank. You’ll likely want to flush your system every three or four months.

How Often Should You Flush Your Black Tank?

How often you flush your black tank depends greatly on how you use your RV. If you travel seasonally, your RV will sit in storage between uses. Thus, you’ll want to flush your black tank after each use. 

You don’t want your black tanks sitting with waste in them for weeks at a time. This will likely result in you coming back to a very smelly RV. It may take you a few extra minutes at the dump station, but you should clean them when they sit in storage.

Full-time RVers may not need to flush their black tank every time. If you find a long line at the dump station, you can wait until you find another. Just don’t wait too long between flushes. 

You can also flush your tanks after every second or third dump instead of every single time.

How Do You Know If There’s Mold in RV Tank?

If you haven’t cleaned your system in a while, you’ll likely have mold in your RV tanks. Most RVers start to notice mold when they begin to smell it.

 If you can smell an unpleasant odor from your sink, sanitize it as soon as possible. If the odor is still present after sanitizing it, you may want to hire a professional to do it for you instead.

Using bleach solutions can easily solve the problem. Just follow these tips to keep your tanks clean and your campers healthy. Do you have moldy RV tanks?

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