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Key Takeaways

  • Properly measuring bleach is essential for safe tank sanitization.
  • Use one cup of bleach per 40 to 60 gallons of tank capacity.
  • Prepare a bleach-water solution before adding it to the tank.
  • Ensure even distribution by filling all plumbing fixtures with the chlorine solution.
  • Allow the bleach to sit for at least four hours before flushing and rinsing thoroughly.

Bleaching your RV water tanks is crucial in eliminating bacterial growth. But how much bleach do you need to sanitize your RV water tanks?

The right amount of bleach will vary, but the general rule is that one cup is good enough for a water tank with a capacity of 40 to 60 gallons. Depending on how foul your tank is, or if you want to kill everything possible, you may want to increase this amount.

Over the years, I've provided valuable insights and practical solutions for maintaining a safe and hygienic water supply within RVs. My extensive knowledge in this domain ensures that the recommendations I offer are accurately tailored to the specific needs of RV enthusiasts. As such,  my expertise will help you effectively sanitize your RV water tanks with the right amount of bleach, ensuring a worry-free and enjoyable camping trip.



How Much Bleach to Sanitize RV Water Tanks

Most RV owners and users will recommend using one cup of bleach for every 40-50 gallons of your water tank capacity. So, if you have a water tank of about 40 gallons, one cup of bleach is enough.

If its capacity is 100 gallons of water, two cups are enough. If the tank is smaller and has a 20-gallon capacity, half a cup is enough.

Some RV-ers will recommend going lighter and using less bleach, for example, one cup per 60 gallons. Others will recommend stronger, but this depends on the tank.

If you want the absolute surety that your tank is sanitized and using less bleach makes you anxious, you can go for a stronger solution.

Why Do You Need to Sanitize RV Water Tanks

Sanitizing a dirty RV tank would make sense to eliminate any potential risks, but what about brand-new tanks or tanks that haven’t been used in a while? Many might think a simple rinse is enough before you can use your RV fresh water tank again.

But there are plenty of reasons why sanitizing is essential, especially during the camping season.

When you leave your RV in storage, there is a very high possibility that harmful bacteria have settled and built up in your hot water tank. Not just in the walls of your tank but also in the plumbing system. The best way to get rid of them is to sanitize the entire tank with bleach.

If not removed, these bacteria can contaminate the water you add in, especially if you’re drinking it. Contaminated water can cause problems like gastrointestinal issues, diarrhea, dehydration, etc. Keeping the fresh water system sanitized helps prevent these issues.

Stale water in the tank can also result in unpleasant smells. By sanitizing, you can eliminate these odors so that any freshwater you add will not retain these smells.

Note that a gray tank, which contains waste water from RV sinks, does not require sanitization in the same way as a freshwater tank. Instead, they need regular cleaning and maintenance to prevent odors and clogs, but don't use bleach for sanitization.

Also, when sanitizing the fresh water tank with bleach, it's important to ensure that the bleach solution is thoroughly distributed throughout the entire system, including the pipes, drain valves, and the water pump.

Is Too Much Bleach Bad For the RV?

No, the likelihood of harming your RV’s water system by using more bleach is very low. In fact, when using bleach for sanitizing, you’ll leave the solution in the fresh tank for several hours.

Since you let the bleach solution sit on the shelf in plastic containers for months, you can be sure it’s not likely to harm your water system in a few hours’ time.

If you think you’re not using enough bleach, even two or three cups per 50 gallons is fine, and you won’t be harming your system in any way.

On the other hand, if you’re worried about accidentally ingesting any leftover traces of bleach, you can flush out your tanks several times or until you can no longer smell the bleach mixture for your peace of mind. However, this is not likely to cause any issues.

If you’re going by smell, it may take several rinses and flushes to remove it completely. While the smell of bleach lingers, the chemical gets washed away quickly, so you have little to worry about.

How Do You Know You’re Using Enough Bleach

So, there’s no such thing as ‘too much’ bleach, but what about ‘too little’?

There is no such thing as ‘too little’ either. The purpose of bleach is to sanitize the RV’s fresh water system, but you can’t eradicate every possible threat.

First, you’re not trying to have pure water anyway; you’re just trying to make the water safe to drink. Even our water systems at home don’t have 100% clean water. Therefore, the amount of bleach you add is entirely up to you.

Plenty of RVers will add a teaspoon of cleaning solution to the freshwater tank when they fill it with water. Bleach is safe to ingest at this low level since it spreads throughout the water and becomes extremely diluted.

Some water districts and swimming pools also add bleach mixture to the water to get rid of certain pathogens, so if you’ve ever been to any of these, you’ve probably already ingested some amount of bleach.

Therefore, you can add any high or low bleach for regular water lines with the same end result.

However, if you know that your RV’s fresh water tank is heavily polluted, you should use more bleach to eliminate the contamination and any possible pathogens. Since the water is already polluted, you definitely don’t want to ingest anything in it.

In such cases, you should add a cup or two of chlorine bleach and leave it for several hours to sanitize it properly.

How Long Should You Leave Bleach In Your RV Water Tank

How long you should leave the bleach depends on the size of the RV’s freshwater tank and how much bleach you used in said tank. If you’ve used only a small amount of bleach, you may have to leave it longer, whereas for larger amounts, you can drain faster.

Either case, you should leave it in for at least four to twelve hours. If you’re going for the one cup per 40-gallon approach, four hours is plenty. You may have to go up to twelve hours or more for lesser amounts of bleach.

How To Know When To Sanitize Your Water Tank

The best way to determine if your tank water is clean is to get water from it and check. Don’t drink it immediately since you don’t know if it’s safe for drinking or not.

Hold the water mixture up to light and see if it has any color. Hazy, green, or yellowish water indicates that your tank is not clean and should be sanitized.

White water can be aerated, which means that the air in the lines may have gotten trapped. By leaving it for a few minutes, you can eliminate the air bubbles and check for smell or color.

If your water tank is foul, you may have to remove and clean it out by hand. In fact, cleaning isn't a great solution for a very dirty holding tank, and you may just have to replace the entire system.

How Do You Test if Your Bleached Water is Clean

Water Testing Kit
Water Testing Kit

Testing your RV water to ensure it's clean and safe after sanitizing the tanks with bleach is crucial in maintaining water quality during your travels. Here's how you can do it:

  • Gather Testing Supplies: You'll need a water testing kit, which can be purchased at most RV supply stores or online. Ensure it can test for chlorine levels, as this will be the primary indicator of residual bleach in your city water.
  • Flush the System: Before testing, ensure that all the bleach-water solution used for sanitization is flushed out of your RV plumbing system. Open all the faucets (both hot and cold) and run the water until you no longer smell bleach.
  • Collect a Water Sample: Using a clean container, collect a drinking water sample from a cold-water faucet in your RV. Let the fresh water drain for a few minutes to ensure you're sampling fresh water from the tank.
  • Test for Chlorine: Follow the instructions on your water testing kit to test for chlorine levels in the collected water sample. Most kits will provide color-coded strips that change color based on the chlorine concentration in the water.
  • Interpret the Results: Compare the color of the test strip to the kit's reference chart. The chart will indicate the chlorine concentration in parts per million (ppm). Ideally, you want the chlorine level to be very low or undetectable, which means the bleach has been fully flushed from your system.

Can You Use any Bleach

Unscented Household Liquid Bleach
Unscented Household Liquid Bleach

Not all bleaches are suitable for sanitizing your RV water system. Using unscented household liquid bleach that contains between 5% and 6% sodium hypochlorite as the active ingredient is recommended.

This bleach is commonly found in most grocery stores and is well-suited for sanitizing RV water tanks. It's important to avoid using scented bleach, as it can leave residues and potentially contaminate your water supply.