How to Sanitize Your RV Water Tank & Water System

Does the water from your RV taste bad or smell funky? It’s most likely due to mold and bacteria growing in your water tank. This is why it’s so important to know how to sanitize your RV water tank regularly. Otherwise, you are not only risking your health but also your family’s health; including your pets!

So, we asked RV tank cleaning professional, Jim Tome of Kleen Tank to take us through each step from start to finish how to sanitize your RV water tank.

How to Sanitize your RV Water Tank

This blog article contains affiliate links. Full disclosure here.

How to Sanitize your RV Water Tank and Water System

What’s growing inside your RV’s water tank?

Quite simply, that nasty green and black slimy stuff that sits in your water tank is toxic MOLD.

For a moment, think of your RV water tank like a body of water. When there is aeration and movement like a rushing stream or waves on an ocean or lake, bacteria doesn’t have the opportunity to take ahold to grow.

However, if you allow your RV water tank to sit like that of a pond, the water becomes stagnant. This allows billions of micro-organisms to grow and bond together; creating that green and black slime aka ‘mold’.

Especially in warmer climates, if you don’t sanitize your RV water tank, the inside of it creates the perfect environment for mold and odor-producing bacteria to grow.

But, by consistently using the water in your RV water tank, it presents a similar effect as the rushing stream or waves on the ocean.

However, that’s still not enough to maintain a safe place for your drinking water in your RV. Just like it’s important to occasionally wash and rinse out your teakettle or water pitcher, it’s equally necessary to clean and sanitize your RV water tank in your motorhome or camper.

How often must you clean and sanitize your RV water tank?

If you’re a weekend camper and/or part-time RVer and you use your water system periodically, you should sanitize your RV water tank at least twice a year, no matter how often you use your RV and use water from your water tank.

But, if use your RV full-time and/or use water from your fresh water holding tank frequently, you should clean and sanitize it at least 3 to 4 times a year.

All of that said, whether you’re a weekend or seasonal camper, part-timer or full-timer, if you’re using your RV in warmer environments, you should be sanitizing it more often so you don’t get that dangerous bacteria and mold in your water system.

We also recommend you thoroughly clean, flush and sanitize your water tank when you winterize your camper and/or before putting it into storage. Equally, it’s important to repeat the sanitation process again when you de-winterize your RV to get ready for the next camping season.

Before we get into the actual water tank sanitizing process, let’s talk about how to prepare for this important RV maintenance task. We’ll also share some pertinent safety precautions that need to be taken before, during and after the process.

Preparation and supplies needed to sanitize your RV water tank

How to sanitize your RV water tank - eye protection and rubber gloves

First, you need to park your RV at a full-hookup site with water and sewer. Because you’re going to be using a lot of water.

I might add, this is also a good time to clean your black tank because you’ll need ample water for that task as well. And, it’s easier to keep both maintenance tasks on the same schedule.

But, to avoid cross contamination, do not perform both of these holding tank maintenance tasks at the same time. You should clean and sanitize your water tank before taking on the task of cleaning your black tank.

Clothing and PPE (Personal Protective Equipment)

You’ll need to wear old clothes because cleaning and sanitizing your tanks can be a messy job. We also recommend wearing disposable gloves to protect your skin and safety glasses to protect your eyes from splashes.

Cleaning Supplies

If not already, you’re going to need to hook up your drinking water hose from the campsite spigot to your RV’s water port. You’ll also want some shop towels readily available to clean up any drips or splashes immediately.

Chlorine Bleach & Safety Precautions

To clean and sanitize your water tank, you will need regular household chlorine bleach. Chlorine bleach contains the necessary concentration to disinfect and sanitize your RV water tank and water system. Do not use splash-less bleach as it does not contain the same concentration.

The active disinfectant ingredient in household bleach is sodium hypochlorite. It’s been used for centuries as a disinfectant and bleaching agent. Common household bleach is a very diluted solution of sodium hypochlorite. Really, it’s mostly water but with traces of the chemical.

While not toxic, bleach can be highly corrosive. It can damage or degrade rubber or plastic parts and surfaces, such as water supply and waste disposal plumbing pipes, holding tank seals, and other soft, delicate parts in your RV if left too long. Which is the reason why you need those shop towels ready at hand.

Also, you want to avoid allowing bleach to stay in contact with delicate metal instruments or structures (such as your holding tank’s sensor probes) for more than the prescribed time. We’ll mention that later.

This is precisely why rinsing and disposing of the diluted bleach-water solution used to sanitize your RV water tank is so critical.

All of that said, household bleach is perfect for destroying bacteria, molds and mildews as well as most viruses. 

NEVER mix bleach with any ammonia-based cleaners. Doing so will create toxic chloramine gases and an explosive called nitrogen trichloride. (That’s BAD!)

The inhalation of those noxious fumes associated with the mixing of household cleaners can lead to pulmonary irritation and pneumonitis. In higher concentrations, the combination of hydrochloric acid, ammonia, and oxygen free radicals may cause corrosive effects and cellular injury, resulting in pneumonitis and edema.

So, again, never mix anything other than clean water with bleach!

Lastly, household bleach degrades quickly; especially when exposed to sunlight. Always store bleach in a cool, dry environment in thick, opaque plastic (like the container it comes in!) or glass bottle.

Better yet, just buy a small bottle of household bleach; enough to sanitize your RV water tank and be done with it. Then you don’t have to worry about storing it safely or it degrading over time.

So, now let’s get down to the nitty gritty of how to disinfect your RV water tank.

How to Clean and Sanitize your RV Water Tank and Water System

The disinfecting process of your coach’s water tank is actually quite simple. You are basically going to get a diluted mixture of household bleach and clean water into your fresh water holding tank.

Do not a regular garden hose. Only use your white or blue drinking water hose specific for water transfer from the spigot at your site to your RV’s water port.

How to Sanitize RV Water Tank - Bleach to Water Tank Capacity Ratio Banner

Some recommend to mix the bleach in a bucket or container with water and then pouring into your water tank. 

However, that will just make a big mess that can result in bleach coming in contact with your skin, clothes, the side of your RV, and even on the ground. We think our process below is easier with less mess and hassle.

Step by Step Directions

Step 1: Bypass all the water filters in the RV (ie. fridge filter and under sink filter). Usually there’s a small toggle or lever that allows you to do this.

If there is no way to do that, simply remove all water filter cartridges from each of the filter housings until you are finished with your holding tank sanitization process.

Step 2: Bypass your RV’s hot water tank.

Step 3: Empty your gray tank completely into your site’s sewer hole. Then, close your gray tank valve so it does not drain into the sewer hose.

Step 4: If your RV has a gravity fill water port, use a funnel to pour the appropriate amount of bleach into the fresh water tank. 

OR using the same funnel, pour the appropriate amount of bleach into your RV drinking water hose before attaching the hose to the fill port. Using this method allows the bleach to somewhat clean and sanitize your hose.

Step 5: Connect one end of the water hose to your RV’s fresh water fill port. Connect the other end to your site’s potable water spigot.

Step 6: Fill the fresh water holding tank with potable water. This will mix the bleach in your water tank. You’ll need to monitor how full your water tank is getting. Do not allow the water to spit out of the water overflow port.

Step 7: Once your water tank is full, briefly turn on every water faucet in your RV. This includes your kitchen and bathroom faucets, shower head and even flush the toilet. But only flush until you detect a distinct bleach smell from each faucet, shower head and toilet. Then, shut them all off quickly. This ensures that all pipes and other plumbing fixtures have the bleach mixture to sanitize them.

Step 8: Allow your RV’s water system and fresh water tank (now nearly full of bleach-y water) to set for a minimum of four hours or even overnight. 

Step 9: Once the bleach mixture has set, pump out the water from your RV’s fresh water tank by turning on all faucets, shower head and toilet into your RV’s black and gray tanks. You need to monitor your tank gauges to not overfill them.

Step 10: Open your sewer valve to now allow the bleach solution that’s now in your sewer tanks to empty into your campsite sewer through your RV sewer hose.

Step 11: Once your tanks are completely empty, repeat steps 7 and 8 until there is no residual bleach odor coming from any of your faucets, shower or toilet into your black and gray sewer tanks.

Step 12: Empty your black and gray sewer tanks completely and close the valves again.

Step 13: Once your RV fresh water tank is completely empty, refill it again with clean, potable water only. Allow it sit for 1 hour without draining or using that water.

Step 14: Pump the water through your faucets, shower and toilet again into your black and gray tanks one last time.

Step 15: Empty your sewer tanks one more time.

Step 16: Reattach all of your water filters.

Step 17: Fill your water tank with clean potable water as needed.

Your RV water tank and complete water system is now disinfected and sanitized until next time.

Final thoughts on how to sanitize your RV water tank and water system.

RV Fresh Water Tank - Child Drinking Water

We hope this tutorial helps to guide you through the proper process of cleaning and sanitizing your RV’s fresh water tank and fresh water system. Now, you can rest easy knowing your family won’t get sick from the water stored in your water tank. Just be sure to repeat this process as prescribed earlier in this article.

About our Guest Author

Jim Tome of Kleen Tank

Jim Tome, owner of Kleen Tank, an Authorized All Pro Water Flow dealer, has been an RVer for over 15 years. His company provides RV holding tank cleaning services throughout the U.S., but mostly in the Midwest. He posts weekly articles on RVing, tips and advice, and relevant topic on the blog at He attends RV rallies throughout the year, giving seminars, and teaching RVers about their RV’s holding tanks and waste handling systems. 

Other articles worth reading:

Clear Source RV Water Filter System

RV Hot Water System Cleaning and Maintenance

RV Upgrade: Our Fifth Wheel Anderson Kantleak RV Water Service Panel

Plumbing and Drain Maintenance

Valterra RV Sewer Hose Storage


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17 Replies to “How to Sanitize Your RV Water Tank & Water System”

  1. I was just wondering, is it 1/4 cup of bleach (2 oz) or 4oz (1/2 cup) per 15 gallons of fresh water?
    Thank you!

    1. Brenda, thank you for following our blog. The answer is: “To sanitize the water system in your RV, use a quarter cup (two ounces) of household bleach for every fifteen (15) gallons of water your fresh water tank holds.” Hope that helps! -Dan & Lisa

  2. Where do you suggest we dump the bleach diluted water from the gray tank after we flushed the lines? 🙂

    1. Hi Jaime, thanks for following along and taking time to read our blog. Anytime you flush your tanks, it should be at a designated dump station or sewer connection at a campground, RV park, rest stop, etc. Never dump on the ground where ground water may lead to rivers, streams, lakes or the ocean. Hope that helps! -Lisa and Dan

    2. Always dump your wastewater into a designated dump station or sewer for proper disposal. Although the bleach would deteriorate in the sunlight, It’s never a good idea to pour bleach onto the ground. It will kill or make sick everything it comes in contact with until it breaks down. This includes essential bacteria, fungi, and more.

    1. Hi Mike, thanks for asking. The only bleach is through your fresh water tank when you sanitize. There are no special solutions for your hot water tank specifically. -Dan

    1. Hi Aaron, good question. Hook up your fresh water hose (white one) to your RV’s fitting. Before hooking up the other end to the water spigot, carefully pour the prescribed amount of bleach into the hose using a funnel. Then, being careful not to have it spill out while hooking up the hose to the water spigot. Then turn on the water on. Hope that helps! Safe travels!

  3. I want to clean the RV’s water tank without detergents. I also have a way to clean the water tank, you can read it:
    Step 1 – Empty the water tank and then check the anode rod. If it is in a bad condition, like if it is heavily corroded or has clear signs of deterioration, then you need to replace it first before you continue with the next steps.

    Step 2 – If the anode rod is still in good condition, use a rinsing rod to flush out any dirt from inside the water tank.

    Step 3 – If you live in an area with hard water, the inside of the hot water tank might have gotten clogged up with all sorts of mineral deposits. To get rid of these mineral deposits, add a couple of tablespoons of white vinegar into a gallon of water and then pump it into the water heater tank.

    Step 4 – Another way to go about this is to open the pressure release valve and pour the water and vinegar solution through the top poof of the heater using a funnel. Wait a couple of minutes and then drain the water tank completely.

    1. Hi Samantha, you’re suggestions are pretty much everything we’ve posted in the blog, so we must be doing something right. Not too sure about Step 4. I’m curious, are you a certified RV technician? Thank you for reading.

  4. How long is the water that you have left in the fresh water tank OK for continued future use after the RV has been standing idle?

  5. Cleaning the RV fresh water tank is necessary to eliminate any potentially hazardous pollutants that may be present. Ingesting algae and dangerous bacteria can raise the likelihood of health problems such as vomiting, fever, and gastroenteritis. Thank you for sharing your experience.

  6. Thanks for these helpful tips. Cleaning the RV holder tank sensors is an essential skill for all motorhome owners.

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