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How to Clean and Sanitize Your RV Water Tank

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Water is an essential element of RV living, from washing dishes to showering to, well, drinking water. It’s best to stay ahead of the curve, but what do you do when you start noticing a strange taste or smell coming from your RV’s water system? Fear not, dear RVers, because we’re here to guide you through the process of cleaning and sanitizing your RV water tank. Trust us, you don’t want to be stuck with funky-tasting water on your next adventure. So, grab your gloves and safety glasses, and let’s get to work!

Table of Contents

How Often Should You Sanitize RV Fresh Water Tank?

The experts vary from once a year to every time you refill your tank.  Most end up doing it annually, usually while de-winterizing, or after they’ve let fresh water sit in the tank for more than a few weeks.  I think that is a good guideline to stick by to stay ahead of any smells or weird tastes!

Preparing for Cleaning

When it comes to cleaning and sanitizing your RV water tank, preparation is key.  First, let’s gather some supplies:

Steps to Cleaning Your Tanks

Park in a place where the fresh water can drain safely (not into your neighbor’s spot).  I usually try to find a spot with a little bit of a grade for the water to flow away.  You don’t want to be tracking water or mud in and out of your camper.  It’s also easier if your gray tank is empty beforehand.

If you’ve had your hot water heater running, you’ll want to shut it off and run the hot water for a minute or two to cool down the tank. You definitely don’t want to be draining steaming hot water!

Now you’ll want to shut off your water pump and open up all of the faucets.  This relieves any pressure in the system and also allows the water to drain easier.  

To drain your hot water heater, you’ll first want to relieve any pressure by opening the pressure relief valve.  You’ll then remove the anode rod (great time to inspect and replace if needed!), and let the water drain out.  I usually rinse out the hot water tank at this point to get rid of any sediment.

Now you’ll drain your fresh water tank.  Locate the fresh water tank drain and the low point drains.  My RV uses a white hose for the tank drain and it’s located right next to the fresh water tank.  The low point drains are usually red and blue (for hot and cold lines) and located at the rear of the RV.  

I usually inspect the lines for cracks and wear and replace anything if needed.  I also replaced the caps with valves for ease of use for the next time!

How much bleach to sanitize your RV water tank

We’ll have some time to kill while the water is draining.  Let’s get our bleach measured out!  The general rule is to use ¼ cup of bleach per 16 gallons of water.  For example, my camper has a 40-gallon tank.  40 / 16 = 2.5.  2.5 x ¼ = ⅝ cups of bleach.  You don’t want to pour the bleach directly into your tank, so you’ll want to dilute it into at least a gallon of water.

Once the water is done draining, close all of the drains and put your hot water heater back together.

Adding your bleach mix to the tanks

Most RVs allow you to use a funnel and pour directly into your tanks.  Mine does not, so I pour the mix into the hose (a short hose for this is handy) and then either use the hose to pour it into my tank, or then hook it directly up to my water source.

Now, you’ll start filling your tank up.  Once the tank is full, turn on the water pump and turn the water faucets on (if they weren’t already open) allowing the mix to flow through the system.  Allow it to flow through for at least 2-3 minutes.  Don’t forget your shower and any outside faucets/showers.  Now you see why we wanted an empty gray tank!

How long to leave bleach in your RV water tank

Close all of your faucets.  Now you’ll want the mixture to sit in the tanks and lines for 24 hours, or at least overnight.  You don’t want this mixture to stay in any of your tanks (including your gray tank) for more than 24-48 hours.  

Bleach isn’t great for soil, grass, or plants.  One way to dispose of it is to turn on your faucets and pump the water into your gray tank, and dispose of it in a dump station or sewer.  Or, you can drain it into buckets via the water tank and low-point drains.  If you aren’t concerned, just drain your tanks as you did before.  Either way, you’ll want to drain the tanks and lines completely using the low-point drains to get it all out.

Flushing your tanks

With the drains back on, you’ll want to start refilling your water.  Once it’s about ⅓ full, turn on the faucets and flush out the lines as well.  If you’re lucky enough to be hooked up to the sewer, just leave the gray tank drain open.  You’ll want to flush until you can’t smell the bleach coming out of the faucets.  This may take a few flushes.  If you use any kind of in-line RV water filters that would have come in contact with the bleach, you’ll want to replace those as well.

If you’re heading out for a trip, go ahead and fill your tanks and you’re good to go.  If not, go ahead and empty the tanks again to prepare for storage.

Keeping your water fresh

A few ways to keep your water fresh smelling and tasting:

  1. Use a dedicated hose to fill up
  2. Fill up with known good potable water
  3. Use a water filter when filling
    1. Or install a water filtration system
  4. Don’t let water sit for more than a week.  
  5. Be sure to empty the tank and lines in between uses.


In conclusion, keeping your RV water tank clean and sanitized is a crucial part of ensuring a healthy and enjoyable adventure on the road. So, roll up your sleeves, follow these simple steps, and let the good times flow as you embark on your next journey with confidence, knowing that fresh, clean water awaits you at every turn!

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