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How Much Bleach to Sanitize the RV Tank?

Writen by Dane Heldt

Fact checked by Robert Clark

How much bleach to sanitize the RV tank? Answering this question is a must for anyone looking to have a comfortable trip. In fact, keeping your RV’s freshwater tank clean and bacteria-free is an essential part of the RV lifestyle.

How Much Bleach to Sanitize the RV Tank

Otherwise, you might not have access to drinkable water during your trips. This issue makes sanitization a vital piece of the RVing experience. Due to this, knowing how much bleach is needed for this process is crucial.

How Much Bleach to Sanitize the RV Tank


Sanitizing your RV tank effectively will require a bleach solution. You’ll need to add a ¼ cup of bleach for every 16 gallons of water within your freshwater RV tank. This measurement will equal one ounce of bleach per eight gallons.

As a result, you should make your calculations based on these measurements. Let’s say you have a 32-gallon RV fresh water tank on your motorhome: you’d need 2/4 cups of bleach to sanitize your system, keeping things bacteria-free and clean.

But please don’t add the bleach right into your freshwater tank. It needs to be diluted first with a gallon of water for each ¼ cup of bleach. The bleach will be a little too potent and render your freshwater tank unusable without it.

However, calculating the right amount of bleach and mixing the solution is only part of the process. You’ll need to follow these five steps to sanitize your RV’s freshwater tank successfully.

Shut Off Your Water Heater and Drain Out Your Freshwater System

It’s essential to make sure your water heater is off before draining your freshwater system. If you don’t, it’ll end up damaging the water heater. You’ll instead need to shut it down and let it cool before draining water from your RV’s freshwater tank.

It would be best to have the water pump on to ensure all the water gets removed before sanitization starts. It’s the only way to make sure this entire process ends up being as safe and effective as possible.

Create the Solution and Add it to Your RV’s Tank

Remember, the correct measurements are ¼ cup ounce of bleach per 16 gallons. In other words, a 40-gallon RV tank would require 2.5/4 cups of bleach. You should then add at least 2.5 gallons of water to dilute it effectively.

Once you’ve got the right solution, pour it into the tank using a funnel. It’s a crucial step to prevent the mixture from spilling or being challenging to use. I always recommend wearing gloves when creating these types of cleaning solutions.

Fill Your Tank with Potable Water

Your next step will be filling the tank with potable, clean water. It’s necessary to ensure you fill the tank entirely with it, which helps thoroughly complete the sanitization process. You’ll have to make sure the water/bleach solution gets pumped through your entire freshwater system, as well.

It’ll require turning on all your RV’s faucets to let it spread through them. Once your water’s circulated through each tap, you can start shutting them off again.

Allow The Water to Sit Overnight

The bleach/water solution won’t magically sanitize your system. It’ll take some time, about 12 hours or so, to do a thorough, adequate job. An easy method would be letting it sit in your freshwater tank overnight. Therefore, you won’t have to think about it.

Drain the RV Tank and Flush Your System

After 12 hours, you’ll need to drain out all the water again. You should then refill your tank with fresh water and start pumping it through the entire system via a water pump. Make sure to open all your faucets and flush out the system until the horrible bleach smell disappears.

You might have to do it a few times for the bleach smell to vanish entirely. But it’s nothing to worry about, as doing this step more than once won’t hurt your RV. I’d advise continuing to flush your system even after the odor is completely gone.

It’s a precaution to ensure all the chemicals are truly gone from the freshwater system. After all, a little extra safety has never hurt anyone. You should then replace any water filters present on your motorhome.

After replacing your filters and flipping the water heater back on, the freshwater system should be more than ready for usage.

Benefits of Sanitizing Your RV Tank


Sanitizing your RV tank with bleach is the easiest way to guarantee exceptional water quality. It’ll also remove any doubt about the safety of drinking or using it. If you don’t sanitize the water tank, bacteria could start growing, and other issues might arise that could require expensive repairs.

How Often Should You Sanitize Your RV Tank

Experts recommend sanitizing your RV’s water tank at least every six months. If you consider yourself a full-time RVer, this six-month schedule should be more than satisfactory. But people who use their rigs regularly might have to do this even more often.

In these cases, I’d recommend doing it every three months. It’ll help compensate for bacteria, mold, or mildew that might build up in stale water. If left unchecked, this stagnant water becomes the perfect breeding ground for those issues and makes your freshwater system unsafe.


These discussions should’ve made finding the right amount of bleach for your RV freshwater tank’s sanitization a breeze:

  • Calculate the right amount of bleach, based on the one ounce per eight gallons guideline.
  • Dilute it with a gallon of water for each ¼ cup of bleach added.
  • Follow our step-by-step sanitization guide.

But if you have any more questions, feel free to use our comment section. I’ll make sure to answer each post as soon as possible. Thanks for reading!

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