How to Sanitize Your RV Freshwater Holding Tank [in 11 Easy Steps]

Fresh, potable water is an important part of our daily lives. We rely on it for drinking, cooking, and bathing. Without potable water, we have to boil and filtrate our water to ensure it’s healthy enough for consumption or other use.

What’s one of the key indicators that something is wrong with your water? It might give off an unpleasant smell. The same thing can happen in your RV’s freshwater holding tank. As the name suggests, this is the tank that provides potable water while you live in your vehicle. If it starts stinking up the place, you need to do something about it right away.

Luckily, an odorous freshwater holding tank is not a sign of serious trouble. It just means it’s time for some sanitizing.

Reasons for Sanitization

There’s one very convincing reason to sanitize your freshwater holding tank: your health! A well-running freshwater holding tank is perfectly good to drink water from. Once that tank becomes dirty and smelly, though, that is no longer the case. You could be drinking a variety of contaminants which could affect your health.

How Do You Sanitize Your RV Freshwater Holding Tank?

Okay, so let’s get into the steps you should follow to sanitize your freshwater holding tank.

First, let’s go over the tools for the job, such as:

  • A replacement anode for your water heater (this one from Rheem has almost five stars on Amazon)
  • Petroleum jelly to grease up the water filter body’s O-ring
  • A water filter wrench to access the internal filter (this one from Geekpure includes a one-inch outlet/inlet water filter housing and is available on Amazon)
  • A funnel with a stopper and long hose; transparent hosing is best
  • Bleach (this two-pack of Clorox bleach on Amazon is available for under $20 and includes 55 fluid ounces per bottle)
  • An internal water filter
  • An external water filter

Do know this is going to be a time-consuming job. While you don’t have to sit there and watch every part of it, you should allocate roughly six to 12 hours for sanitization, aka a whole day.

Now that you have what you need, here’s how you sanitize your RV freshwater holding tank.

Step 1. Clean your funnel hose using the bleach. Fill the hose with bleach and wait 15 minutes. After that, filter the bleach through.

Step 2. Access your freshwater tank and empty it out a little. It should be only half full.

Step 3. Filter the bleach from Step 1 to the freshwater fill.

Step 4. Restore the rest of the water to the freshwater tank. The tank should now be full. If the overflow hose begins spurting water, you’re overfilling the tank.

Step 5. Now switch on your water pump, stopping the freshwater supply as well.

Step 6. Access every faucet in the vehicle, even the hot water faucets. These should all be on and open. The smell of bleach will subtly begin to fill the faucets and then get stronger. Once this happens, close every faucet.

Step 7. Now go back to your freshwater tank. At this point, it’ll have lost some water. You should fill several gallons back in, making sure the freshwater supply is running while you do so.

Step 8. At this point, you can step back and take a break. The sanitization will happen on its own as the bleach filters through the freshwater holding tank. You can let this go on for as little as three hours, but many RV owners recommend six hours. This is especially crucial if you only plan on sanitizing your freshwater tank every six months or so.

Step 9. Once the six hours have elapsed, empty the freshwater tank completely. Then fill it back up with more water. You can use the freshwater supply to make this job easier.

Step 10. Now that the freshwater tank is full, stop the freshwater supply. Instead, you want to access and run the RV’s water pump. Once again, turn on every faucet in the vehicle for water line flushing.

Wait until you smell less bleach. If that doesn’t happen, you may have to empty the freshwater tank once more and refill it.

If that still doesn’t remove the bleach odor, then you can fill five gallons of water and mix it with vinegar (just a quart) and fill the freshwater tank with that after draining it for yet a third time.

You might also want to change out your internal filter if you haven’t and see if that makes a difference.

Step 11. If you’re sure the smell of bleach is totally gone, then you can proceed. Stop running the freshwater supply as well as the water pump. Grease up the O-ring and make sure the filters are all changed out with new ones.

You’re done!

How Often Should You Sanitize RV Freshwater Holding Tank?

This is up to you. Some RV owners opt to sanitize their freshwater holding tanks after getting back to their vehicle after the off-season, so every spring. You may want to sanitize both before and after the off-season if you can.

If you sanitize the freshwater holding tank at least once or twice a year, you shouldn’t have to worry about unpleasant odors catching up with you.

Safety Tips

Like many jobs with your RV, the more you sanitize your freshwater holding tank, the easier it will be. That said, safety first! Be sure to keep these tips in mind during sanitization, especially the first few times you do it:

  • If you’re emptying the hot water heater at any point during sanitization, turn it off first. Let the water flow out completely and then allow the tank to return to room temperature before you touch it. Otherwise, you could severely burn yourself.
  • Avoid spilling bleach during sanitization. This substance can stain clothes and other surfaces. You could also suffer eye tissue injuries, skin burns, and nerve damage if you get bleach near your face. If you’re allergic to bleach, you could also have a bad reaction. To be as safe as possible, wear gloves and goggles or glasses.
  • If you feel dizzy from the bleach fumes, exit the vehicle and get some fresh air. You might want to invest in non-scented bleach for this very reason.


Your freshwater holding tank provides potable water to your RV. To keep this water as fresh as possible, you need to sanitize the holding tank on a six-month (or more) basis. Doing so isn’t so difficult if you follow the steps above. Be safe and good luck!

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