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How to Sanitize Your RV Water Tank

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Time to complete project: 10+ hours

Project difficulty: 1/5

Supplies needed:

  • Chlorine bleach
  • Potable water
  • Measuring cup
  • Gallon-sized pitcher
  • Funnel

After a long day hiking, sightseeing, or just laying in your RV watching TV, there’s nothing quite as refreshing as a big drink of water. But have you ever stopped to think about everything that’s in your water? No? That’s probably for the best.

RV Water Tank

As it turns out, your RV’s water tank is a breeding ground for all sorts of bacteria, fungi, and other things you don’t want to think about (unless you just enjoy thinking about algae and slime, of course). That’s why it’s so important to sanitize the tank regularly — you don’t want to leave a bunch of liquid just sitting in there.

That’s especially true if it’s been some time before you’ve used the RV, or if you’ve had to fill up the tank from a less-than-reputable source. And don’t think you can trust your filter to do all the work, either; while they’re great at eliminating rust and heavy metals, they won’t do much about bacteria and other microbial creepy-crawlies.

Fortunately, sanitizing the water tank is one of the easiest maintenance tasks you’ll have as an RV owner, and with the guide below, you’ll have a squeaky-clean tank in no time.

How to Sanitize Your RV’s Water Tank

In order to have the cleanest water tank in the RV park, you’ll need a chemical that kills everything it touches (except the magnificent hair of ‘80s rockers). That’s right, we’re talking about bleach.

All you really have to do to sanitize your water tank is mix some chlorine bleach in with water and pump it through the system. The bleach will take care of any microbes it comes in contact with, leaving your entire system clean and safe to use.

Warning! Pay attention to that whole “bleach kills everything it touches” thing we mentioned above. While adding some bleach to water can help disinfect it (after an earthquake or other emergency), that’s only true in tiny amounts. We’re going to be using a lot more bleach than would be safe to drink, so don’t drink any water out of your tank until the bleach smell is fully eliminated.

Also, while this task is easy to do, it does take the better part of a day, so it might be a smart idea to wait until you’re home or will be away from your rig for some time. You should consider buying some bottled water as well, in case you get thirsty before the job is done.

Flush the System

The first thing you need to do is get all the water out of the tank. However, before you do that, be sure to turn the water heater off, as it will get damaged if it tries to heat an empty tank.

You should also remove any filters you have on your water system before cleaning it. This is a good time to replace them as well.

Determine How Much Bleach You’ll Need

To know how much bleach you’ll need, you’ll first need to figure out how big your water tanks are. Add up the size of the freshwater tank and hot water tank, then tack on a couple extra gallons for the water lines.

You need one ounce of chlorine bleach for every 8 gallons of water in the system. This needs to be diluted before it gets put in the tank, though, so put the bleach in the gallon pitcher and then add water.

Chlorine Bleach

Pour the Bleach in the Freshwater Tank and Add Water

Using a funnel, dump the bleach mixture into your freshwater tank, and then add potable water in as well. If you use dirty or questionable water, your tank may not end up much cleaner than when you started, so you shouldn’t sanitize your water system if you’re not in a place with trustworthy H2O.

Fill the tank all the way to the top; you don’t want to miss any spots. You’ll also want to pump as much bleach-filled water as possible through the lines to ensure that they get properly cleaned.

Once the tank is full, turn on every faucet in the RV. This will ensure that the cleaning agents get fully distributed throughout the system; after they’ve been on for a few seconds, turn them off again.

Go Take a Hike

You want to give all that bleach some time to work, so you’ll need to let the water sit for at least 10 hours. You don’t have to sit there the entire time, of course, so feel free to leave your RV and go do something fun.

Many people choose to sanitize their RV’s water system overnight for this very reason, while others do it when they’re at home, with other water sources available. 

Another option is to wait until you’re taking a long drive, preferably one with lots of twists and turns. This will agitate the water in the tank, giving it a more thorough cleaning. Be sure you have bottled water on hand if you choose to do it this way, though.

Drain and Flush the System

Open up all the water lines and drain the bleach-filled water from the tank. Once the tank is completely empty, you’ll need to fill it back up and drain it again to rinse it out.

You may have to fill and drain it several times to get all the bleach out. Don’t skimp on this step — remember what we said about drinking bleach (in case you forgot, we’re against it).

We’d recommend draining the tank until the bleach smell is completely gone — and then doing it a few more times, just to be safe.

How Often Should You Clean Your RV’s Water Tank?

While sanitizing the water system is easy to do, it does take a lot of time (and water). Luckily, you don’t have to do it very often.

How often depends on the amount of time you spend in your rig. If you live in it full-time, then you should sanitize the system twice a year or so. If you’re just using it for the occasional long road trip, once a year is fine.

As we mentioned above, though, you should clean the system if the water’s been sitting in there for a long time, or if you’ve had to fill it with water of questionable quality.

After all, it’s like we always say: “Better safe than riddled with diarrhea.”

Alternatives to Using Bleach

While we believe that using bleach is the best way to truly sanitize an RV’s water system — again, it kills everything — many people balk at adding it to their drinking water (or draining it into the environment). 

There are a variety of other products you can use to clean the water tank. Again, we wouldn’t recommend using these instead of bleach, as most of them will get your tank cleaner but not necessarily clean

If you’re willing to take the chance, though, these are popular alternatives:

  • White vinegar: the acid in white vinegar is good at neutralizing bacteria and other microbes, but only when heated to at least 130°F. If you dump it in at room temperature, all you’re doing is making the bacteria smell bad.
  • Hydrogen peroxide: hydrogen peroxide is roughly as effective as white vinegar, and it also needs to be heated to 130°F.
  • Baking soda: baking soda is great for making your water tank look clean, and it won’t affect the smell and taste of your water. It doesn’t do much for killing bacteria, though, so we wouldn’t use it.
  • Commercial cleaning products: if you go to any store that sees RV accessories, you’ll find a ton of different products designed to sanitize water tanks. These vary in how they’re used, so follow the instructions on the package. Oh, and many of them contain bleach, so if you’re hoping to avoid that you’ll need to read labels carefully (and if you are ok with using bleach, it’s probably a lot cheaper to just buy bleach).

Regardless of what you use to clean the tank, the important thing is to remember to do it. Either that, or serve your guests green tea — it does a good job of covering up all the slime.

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