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How Long Should You Leave Bleach in an RV Water Tank?

Part of RV ownership is having a little bit of knowledge about “how to” do things as well as knowing “how long” is going to make your time the most well spent.

This is especially true when it comes to cleaning out utilities like your RV water tank. Your RV water tank is very important for conveniently storing water for later use in the shower, sink, and for your drinks.

There isn’t a limit to how long you should leave bleach in an RV tank. The larger factors of how long bleach needs to be left in your RV tank are how much bleach you are using, and how long you have.

Why does it matter how long your leave bleach in the RV tank?

Let’s start this by saying that you should leave bleach in your RV tank for at least 8 hours. RV owners tend to leave RV in the water tank while waiting overnight in a place where they can refill water.

8 hours allows bleach to get good, deep penetration and dissolve problem areas. If you drive around with bleach in your tank, you’ll also maximize how much of your tank gets a good bleach splash with the movement of the RV.

How much bleach to use for 8 hours?

There are a couple more good rules of thumb here. Use ¼ cup of bleach per 16 gallons of your water tank. 

Using less means the bleach is more diluted and less effective. If you are running low on bleach, you can leave a smaller amount of bleach in longer to achieve the same cleaning effect.

You could also use more bleach and try to move it around more, though more bleach won’t necessarily make your tank “more clean.”

Can leaving bleach in the tank for too long cause damage?

RV owners and mechanics are aware that bleach can damage the seals and gaskets in your tank. This is true, but can be countered easily.

You might feel the need to use more bleach in your tank sometimes, but don’t do it often. An overconcentration of bleach used repeatedly in your tank can cause gradual damage to the seals. Damaged seals are fixable, but still unpleasant when you are talking about a rather important storage tank on your RV.

The best way to keep your tank clean is to, first, follow any instructions that came with the RV or freshwater tank, and second, clean your water tank occasionally with the right amount of bleach.

Note that using too little bleach has no risk of damaging the tank, but is less likely to completely clean the tank. Using chemicals in this situation is really about balance.

Can I leave bleach in the tank for too long?

Not really, with one condition: Don’t leave a large amount of bleach in the tank for too long. If you are using the rule of ¼ cup per 16 gallons, you can leave bleach in the tank for well past 8 hours while not causing any problems. 

Why? Because you are using bleach in the right mixture. Your tank is receiving both water and bleach, which is more helpful than just the sanitizer.

Can I put a large amount of bleach in for shorter?

Got little time before you have to be somewhere, and have a nasty tank? Think twice, then think again before putting more bleach in the tank to make the cleaning process go faster. An over concentration of bleach will impact your tank quickly, so draining it faster will lessen any damage done, but still isn’t a great idea for preserving your tank for as long as possible.


Cleaning your tank correctly with bleach is important for the long term usefulness of the tank. It is possible but not a great idea to use more than ¼ cup of bleach per 16 gallons, with that amount being necessary for at least a night – or about 8 hours. 

When thinking about how long to leave blach in your water tank, consider the future of the tank and whether or not going shorter or longer is going to help much immediately.

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