How to Sanitize an RV Fresh Water Tank & Lines (7 Easy Steps)

To keep the water in your RV “fresh” and avoid making you and your family sick, sanitizing the fresh water tank and water lines is extremely important.

In this quick guide, you’ll learn how to sanitize your RV freshwater system (tank and lines) in 7 simple steps! Plus, learn how often you should do it and what NOT to do (this is important)!

How to Sanitize Your RV Freshwater System

Before you begin…
Sanitizing an RV freshwater tank is a multi-step process that takes time to complete properly. The actual working time, which includes preparation, draining, filling, and flushing the system, might be around 1-2 hours. However, the majority of the time is taken up by the sanitation process itself, where you need to let the bleach solution sit in the tank and lines for between 12 to 24 hours.

What You’ll Need

• Bleach: Household bleach is the main ingredient for sanitizing your RV tank. It’s a powerful disinfectant capable of killing bacteria, mold, and other harmful microorganisms that may be lurking in your water system. Ensure you use plain liquid bleach without any added fragrances or other special ingredients.
• Water Hose: A potable water hose to fill your tank and water system with fresh water
• Measuring Cup: A measuring cup is essential for using the correct amount of bleach. Too much bleach can damage your RV’s water system, while too little may not effectively sanitize the tank.
• Large Pitcher: A large pitcher or bucket with a pour spout is useful for mixing the bleach and water before adding the solution to your tank. This helps ensure the bleach is properly diluted and evenly distributed throughout the tank.
• Rubber Gloves: To protect your skin from the bleach.
• Funnel (Optional): To pour the bleach/water mixture into your freshwater tank if you’re not drawing the sanitizing solution in using the water pump.

And, of course, you’ll need plenty of fresh water for this process. Water is used to dilute the bleach and rinse the tank after sanitizing.

Tip: Check out our guide to sanitizing an RV fresh water tank without bleach if you don’t like the idea of running bleach through your water system.

Step 1: Prepare Your Water Heater and Pump

1. Turn Off the Water Heater: Begin by switching off your water heater. To avoid damaging the tank, make sure to run hot water from your taps for about one to two minutes. This action helps eliminate any hot water from the system and allows the water heater to cool down before draining.
2. Disable Your Water Pump: Remember to turn off your water pump. To ensure complete water drainage, open all the faucets in your RV.

Did you know…
Yes, you should sanitize your RV water heater! Many tutorials will have you bypass the hot water heater, fearing that the bleach or cleaning solution may damage the internal components (like the anode rod). In my experience, and after reading several owner’s manuals for Suburban and Atwood water heaters, it’s recommended to sanitize. Some suggest bleach, while others suggest vinegar. Check your water heater owner’s manual for more information.

Step 2: Drain the Fresh Water From the System

This step is crucial if your RV’s fresh water tank isn’t already empty from winterization. If it is empty, along with your grey water tank, you can skip to the next step.

Locate the Drains

Find the fresh water tank drain and the low-point drains for your RV’s plumbing lines, which are typically located underneath your RV.

These drains are identifiable by red or blue drains extending from your RV’s bottom. However, some RVs might have a different identification system, so refer to your owner’s manual if you’re unsure.

Drain the Water

Once the drains are located, open the low-point and tank drains to drain the water from your freshwater system.

Step 3: Add the Bleach Solution to Your Fresh Water Tank

Next, we need to add our bleach solution to the tank.

But how much bleach do you use to sanitize an RV freshwater tank?

As a rule of thumb, you’ll need approximately a 1/4 cup of bleach for every 15 gallons of water your fresh water tank can hold.

For example, a 45-gallon freshwater tank would need about 3/4 cup (or about 6 ounces) of bleach for sanitization.

Important: Don’t pour straight bleach directly into your freshwater tank. Instead, dilute the calculated amount of bleach in at least a gallon of water.

There are several ways you can add the solution to your water system:

1. Siphon the solution into the tank using your water pump.
2. Pour the recommended amount of bleach into the city water hose, connect it to your inlet, and turn the city water on to fill your fresh water tank.
3. Pour the recommended amount of bleach into the filter housing (remove the filter first) and fill your tank.
4. Pour this bleach mixture into the freshwater inlet on the side of your RV using a funnel.

Step 4: Fill the Tank and Circulate the Bleach Solution

Fill your tank with clean, potable water. This action will distribute the bleach solution throughout the entire tank.

Once the tank is filled, turn on your water pump and open all the faucets and the shower in your RV. Allow the bleach and water solution to flow through all parts of your RV water system for a few minutes.

After this circulation, close the faucets and turn off your water pump.

Step 5: Allow the Bleach Solution to Sit

Let the bleach solution sit in your tank and plumbing lines for 12-24 hours for effective sanitization. Just don’t let it exceed 24 hours.

Step 6: Drain the Sanitized System

After the bleach solution has sat for at least 12 – 24 hours, proceed to drain the system.

Dispose of the Bleach Mixture Responsibly

For this step, ensure that you’re using appropriate disposal methods. If you’ve used bleach, it is advisable to avoid draining your tank directly into the soil, as bleach can harm plant life and degrade soil health.

The best option is to connect your gray water tank to a sewer connection and then run the bleach/water mixture through your plumbing system into this tank. Then, open the low point valve after turning off your water pump, which ensures complete drainage of your freshwater tank.

Step 7: Rinse Your System

The final step involves thoroughly rinsing your system. Fill your tank with fresh water and run it through the entire system, making sure to open all the faucets. Continue this flushing process until there’s no bleach odor.

If your RV comes equipped with a water filtration system, consider replacing your filters after this sanitization process. This ensures that you’ve effectively removed all sanitizing chemicals from your system, and it’s now ready for water use.

After you’ve completed the sanitization process and have replaced any filters, you are now ready to fill your RV water tank with freshwater. Don’t forget to bleed the RV water lines after filling the freshwater tank, so you’re not surprised by sputtering water later!

Do I Need to Sanitize My RV Fresh Water Tank?

If you use the fresh water in your RV to drink, wash dishes, and shower, then yes, it is necessary to sanitize the fresh water tank. Over time, harmful bacteria, algae, and other microorganisms can build up in the tank and the plumbing system. This can lead to water with a bad taste and unpleasant smell, and in some cases, could potentially cause health problems. Proper sanitization helps ensure the health and safety of those using the water.

How Often Should I Sanitize My RV Water Tank?

Typically, I recommend you sanitize your RV’s freshwater system after pulling it out of storage as part of the camper de-winterization process. If you live in your RV full-time, then every six months is a good schedule to set.

But remember, if you notice that the water tastes a bit strange or has a foul odor, it’s time to sanitize the tanks immediately. In other words, don’t wait around for the scheduled sanitization.

Tip: Keep your freshwater system cleaner for longer by only adding filtered water to your tank. And be sure to flush your water system if the water in your tank is over two weeks old. Learn more in our guide on How Long To keep Freshwater In An RV Tank.

How to Maintain a Clean RV Freshwater System

Maintaining a clean RV fresh water tank is important for both the longevity of your RV’s systems and your own health and safety. Here are some tips:

1. Regular Sanitization: Sanitize your freshwater tank at least once or twice a year as part of your regular maintenance routine. This helps to remove any build-up of bacteria, algae, and other microorganisms. If your RV has been in storage for a while or if you’ve been traveling in areas where the water quality might be questionable, you may want to disinfect the RV water tank and system more often.
2. Use Clean Water Sources: Whenever possible, fill your tank with water from a trusted source. Water quality can vary greatly from place to place, so be mindful of where you’re sourcing your water. Unfortunately, it’s impossible to know for sure if the city water supply at an RV Park, campground, or any public place provides safe water without testing it. This is why I always use a water filter, which is the next tip.
3. Use a Water Filter: Filtering the water that you put into your tank will help remove impurities and improve the taste of the water.
4. Keep It Sealed: When not in use, make sure your freshwater tank is properly sealed. This helps to prevent contamination from dirt, dust, insects, and other potential contaminants.
5. Regular Use and Emptying: Stagnant water can be a breeding ground for bacteria. If you’re not using your RV for a while, it’s better to drain the water system rather than leave water sitting in the tank.
6. Monitor for Leaks: Regularly check your system for leaks. A leak in your freshwater system can introduce contaminants and also lead to other problems in your RV.
7. Replace Damaged Components: Regularly inspect your freshwater system for any damaged parts, such as seals, hoses, and the tank itself. Replace any damaged parts immediately to prevent contamination.