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How Often Should You Drain an RV Water Tank?

Having fresh, clean water while you’re RVing is important. However, many RVers fail to realize that a refreshing glass of ice-cold water could lead to health issues.

Letting water sit in an RV’s water tank for too long can cause a situation for you and your RV. So how often should you drain an RV water tank? Let’s take a closer look and see!

What Is an RV Water Tank?

RV water tanks are storage tanks that manufacturers typically mount to the frame of the RV during construction. These tanks allow RVers to haul water wherever they want to enjoy their RV. This could mean boondocking on public lands in the middle of the desert or a rustic campground that doesn’t provide water at the campsite.

RVers use the water in a tank for bathing, drinking, and cleaning, like in a typical home. An electric water pump will move the water from the tank to the RV’s faucet, fixture, or toilet.

RV water tanks can range from smaller 10-gallon tanks on Class B motorhomes to over 100-gallon tanks on large toy haulers and Class A motorhomes. However, a gallon of water weighs approximately 8 pounds, meaning you could add hundreds of pounds to your rig when filling your RV water tank.

How Often Should You Drain an RV Water Tank?

How often you should drain your RV water tank will depend on how you’re using your RV. To ensure the water in your tank stays fresh, we recommend emptying your tank at the end of every trip. This is especially true if there will be more than two weeks between trips, and the water will sit stagnant in your tank between trips.

On the other hand, if you’re traveling full-time in your RV or refilling it every weekend, you may never need to empty it. However, if there will be more than two weeks between refills, pull the plug and drain your water tank.

Pro Tip: Use our guide on How to Drain an RV Fresh Water Tank to make the process quick and easy.

RV connected to hose emptying water tank
Empty your water tank at the end of every RV adventure.

What Happens If You Leave Water in Your RV Freshwater Tank?

The longer water sits in your freshwater tank, the more likely it is to develop a plastic taste and smell. More seriously, water sitting stagnant can grow mold, algae, and bacteria that can negatively impact the health of anyone who consumes it. You could take a major risk by allowing water to sit in your RV’s freshwater tank for too long.

Can You Pull or Drive an RV with the Freshwater Tank Full?

Traveling with a full freshwater tank is a highly debated topic in the RV community. Some RVers do it regularly, and others swear they’d never consider trying it. To make matters worse, some manufacturers state that their rigs can handle it, and others warn against it. So there’s no confusion, check with your RV’s manufacturer.

Because of the incredible increase in the weight of a full freshwater tank, the bumps and potholes along the way can cause issues. If there’s no water available where you plan to camp, we recommend finding the closest possible water source to your campsite and filling up your freshwater tank. 

However, it may be worth investing in a portable water bladder or water tank to haul the water to your RV.

Campers sitting on top of their RV
Ensure you always have clean drinking water by sanitizing your freshwater tank regularly.

Is It Necessary to Sanitize the Freshwater Tank in an RV? 

You should sanitize your freshwater tank and your RV’s entire freshwater system at least twice a year. If you’re traveling full-time in your RV, you may want to do it three or four times a year. 

Luckily, sanitizing your freshwater tank and system is a project that just about every RVer can handle themselves. However, the process will put your RV’s plumbing system out of commission for at least 12 hours, and you’ll want to have a sewer connection.

Drain the Entire System

First, you need to drain the entire freshwater system. This means opening drains for the freshwater tank. You also want to open the low point drains, water heater (make sure it’s turned off), and all fixtures connected to the system. Check your owner’s manual if you’re unsure of where these are on your rig.

After getting all the water out of your system, you need to bypass the water heater. You can do this by adjusting the knobs on the water system. Again, check the owner’s manual that came with your RV if you’re unsure of how to do this on your specific RV. It’s not necessary or recommended to add bleach to your water heater.

Clean the System

You’ll need to run a bleach-water solution (one cup of bleach for every 50 gallons) through the entire system. Many modern RVs come with siphon features that make this incredibly easy. Simply keep the appropriate ratio of bleach-water solution in a bucket and use a hose to siphon the bleach into your freshwater tank until it’s full.

Once the tank is full, use the water pump to move the cleaning solution from the freshwater tank to the fixtures. You want to run water through each fixture until you can smell the bleach solution. Don’t forget outside kitchen sinks or any outdoor shower connections.

The bleach-water solution needs time to do its job. This typically takes approximately 12 hours, which means you cannot use any of the faucets, toilets, or fixtures in your RV. You’ll want to use the campground’s facilities or have another easily accessible option. Some do this before heading to bed and finish the process first thing in the morning to minimize the inconvenience.

Drain Again and Refill

When the bleach solution has had time to do its job, you must drain the entire system again. The best way to do this is to turn on several faucets and open the gray tank dump valve to avoid filling your gray tank. Let them run until you’ve emptied the fresh water tank and all fixtures of the solution.

You’ll then need to refill the freshwater tank with clean water. Run water through each water source in your RV until the bleach-water solution is no longer present. Don’t forget to turn off the bypass for your water heater and give it time to fill up with water before turning it back on.

RVs parked by water at sunset
Having fresh, clean water while you’re RVing is crucial.

How Often Should an RV Water Tank Be Cleaned?

How often you clean your RV water tank will depend on how you’re using your RV. Since most RVers aren’t traveling full-time, it’s best to clean it at the start and end of each camping season. This means you’re likely doing this process at least every six months.

On the other hand, those who use their RVs to travel full-time will want to increase the frequency. Because they’re constantly filling up at different locations and depend on their water system more than others, doing this maintenance every three or four months is wise.

Should I Add Bleach to My RV Freshwater Tank?

Bleach is incredibly corrosive to plastic and can be harmful. You should only add bleach to your RV freshwater tank after diluting it according to the one cup for every 50 gallons ratio. You can cause severe damage to your freshwater tank and plumbing system if you let pure bleach sit in it.

Pro Tip: Before you hit the road with full tanks, find out whether or not you can travel with your RV tanks full.

Should an RV Water Tank Be Drained After Every Trip? 

Most RVers will benefit from draining their RV’s water tank after every trip. However, it’s unnecessary if you’re traveling full-time or use your RV every weekend. Emptying your fresh water tank is typically very easy and doesn’t take much time. 

When in doubt, it’s a good idea to empty your tanks and fill them up before your next trip. This way, you won’t have to worry about the freshness of the water in your system.

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