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How Much Bleach to Sanitize an RV Water Tank? (Expert’s Guide)

Written by Stephen Ryan / Fact checked by William Turner

how much bleach to sanitize an rv water tank

A lot of RVers have this question, “how much bleach to sanitize an RV water tank”? We need to know the exact amount to kill pathogens and keep them at a safe level. A clean RV fresh water tank will save you from a lot of diseases.

Actually, I’ve seen a lot of variations from different sources, but the rule of thumb is to use one cup of bleach to sanitize 50 gallons of water in an RV tank.

If you want to learn more about RV water tank sanitization, here are some great details to know.

Table of Contents

Why Sanitize an RV Water Tank


Sanitizing RV water tank units is essential because microbial growth can develop over time, even if you use the tank frequently. These tanks should be disinfected at least twice per year and more often if they aren’t used a lot.

Proper maintenance will also give you fresh drinking water that’s safe for cooking and other activities. An RV fresh water tank sanitizer will also prevent the growth of algae that can cause horrible taste and biofilms that can harbor viruses.

Bleach is often used because it’s proven effective, affordable, and accessible.

So, How Much Bleach Is Required?

The amount of bleach needed for sanitation depends on the volume of the RV tank. If you don’t know the volume, follow the formulas here.

Generally, we’ll need one cup of bleach for every 50 gallons of water. Hence, if your water tank has a capacity of 25 gallons, use ½ cup of bleach. If your water tank can hold 12-13 gallons of water, use 1/4 cup.

What Type of Bleach to Use?

You can use any household liquid bleach containing 5-6% sodium hypochlorite. Any brand will do as long as you don’t get the scented variants or those with any special ingredients.

Experts warn against using the splash-less version as it uses an entirely different formula. It cleans, but it doesn’t sanitize.

I prefer to use the Clorox Regular Bleach because its formula is designed to disinfect and kill germs up to 99.9%. Besides cleaning the RV water tank, you can also use this cleaner on other surfaces.

When to Sanitize the RV Water Tank?


Most experts suggest sanitizing water tanks at least twice per year. However, if your freshwater already tastes or smells horrible, you may need to sanitize it immediately for your safety.

One way to determine whether it’s time to sanitize RV water tank with bleach is to fill a glass of water. Hold the glass up to sunlight and check its quality. If the water looks hazy and has already turned green or yellow, then it’s time to disinfect.

If the water appears to be white, don’t sanitize just yet because it may only be aerated due to the air in the lines or water pump. Let that glass of water sit for a couple of minutes to vanish all the bubbles.

Finally, if it gives a horrible odor, like rotten eggs, then the water needs to be sanitized.

It might also be a great idea to sanitize the water tank if you’re taking it out from storage after a long time. You never know what types of pathogens might have developed within that period.

Adding Bleach to RV Water Tanks

First, empty out the tank and clean it well, then fill it with about a quarter full of clean water. Add the necessary amount of bleach, then fill the tank completely with water while mixing thoroughly. Close the lid and let it sit for 24 hours.

Because this process is time-consuming, start your tank sanitization at least 3 days before you need to use your RV. This prevents any last-minute panic before trips.

If a pump is connected to your tank, run it for an hour to let the solution pass through it and the hoses. If there’s no pump, fill the hoses with the disinfectant, then let it stand for 24 hours. Finally, drain out the disinfectant, then connect the hoses to the tank to prepare them for use.


We hope we shed some light on your dilemma of how much bleach to sanitize an RV water tank. The general rule is one cup of bleach per 50 gallons of water. You can always add more bleach to cut the disinfecting time as it usually doesn’t hurt.

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