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How Long Can You Keep Fresh Water in Your RV Tank?

How Long Can You Keep Fresh Water in Your RV Tank?

Using an RV fresh water tank is a relatively simple matter. How to fill it, how to hook up to city water, how to monitor how full it is, how to keep it clean – these are all pretty straight-forward processes. But there’s one important piece of information that often gets overlooked, and that is how long to keep fresh water in an RV tank.

If water sits in a tank for too long, it could cause a host of issues including unsafe drinking water. To learn how to avoid that unhealthy situation and more, keep reading!

How Long Can You Keep Fresh Water in Your RV Tank?

Two weeks is the simple answer to how long to keep fresh water in an RV tank IF you aren’t using the water and refilling during that time.

How long to keep fresh water in RV tank

When water sits unused in a tank, it can become unsafe and therefore undrinkable.

If you use all your fresh water and refill your tanks every week or two, there shouldn’t be issues as long as you keep a clean tank. But, when water sits unused in a tank, it can become undrinkable.

Let’s look at why this happens and what you can do about it:

Does Fresh Water Go Bad in an RV Fresh Water Tank?

Believe it or not, water can “go bad”. If you keep water in your fresh water tank for an extended period, not only could it affect the taste of the water, but it may become unsafe to drink.

Why You Shouldn’t Keep Water in Your Fresh Tank for More Than 2 Weeks Without Using

Since your tanks are plastic, water sitting stagnant inside the tank can assume a plastic smell and/or taste. Worse, it can also grow mold, algae, and bacteria.

If you filled your freshwater tank with water from non-municipal sources (think well water), as many of us do, these issues are more likely to develop. The water can become unfit to drink, cook with or shower in, depending on conditions (heat, for example) and how clean you keep your tank.

Using Old Water from RV Fresh Water Tank

How long to keep fresh water in RV tanks also depends on the intended purpose. If you want to use the water just for flushing your toilet, for example, no harm there. But most of us find many other uses for the water in our fresh water tank. In addition to showering and cooking, how about washing dishes, brushing your teeth, or giving pets a drink?

These are important considerations to keep in mind when tending to the condition of a fresh water tank.

How To Keep Your Fresh Water Tank Clean and Keep Water Fresh

How long to keep fresh water in your RV tank also depends on the cleanliness of your tank. If you maintain your tank well by keeping it clean, you have a far lower risk of mold, algae, and bacteria developing.

Use bleach to sanitize your fresh water tank and lines

Routine sanitizing your fresh water tank ensures that the water you store in that tank stays cleaner for a reasonable period of time.

So let’s look at some tips to keep your drinking water safe longer.

Sanitize Your Fresh Water Tank

A critical part of RV living is sanitizing your fresh water tank. Regularly sanitizing the tank ensures that the water you store in that tank also stays clean.

The standard method of sanitizing a fresh water tank is to add a bleach and water mixture. Using a ratio of 1/4 cup of bleach for every 15 gallons of tank capacity, add this mixture to your fresh water tank.

Next, top up your fresh water tank with city water. Then, one faucet at a time, open all your water lines, and run it until you can smell bleach at the faucet.

Let your tank sit for 8-12 hours, then drain the bleach & water mixture out. Then refill the tank with fresh water, and run water up through all the faucets to flush out the lines. To do this, run the water until it doesn’t smell like bleach anymore. You’ll probably need to fill and empty the tank a couple of times to clear everything out, but you don’t need to wait 8-12 hours for subsequent flushes.

After that, fill your tank and use it as normal with confidence.

If you aren’t using your tank, leave it empty until you’re ready to hit the road again, then fill it with fresh water before your trip.

Culligan RVF-10 inline RV water filter

An inline water filter is inexpensive reassurance that the water you’re adding to your fresh water tank is clean.

Use an Inline Water Filter

Another way to keep fresh water in your tank longer is to use only filtered water. An inline unit filters all water entering your RV, removing bacteria or sediment, ensuring your tank has clean water.

An inline water filter is easy to use and inexpensive. Just attach it to your fresh water hose, then fill your tanks as usual.

Keep Your Potable Water Hose Clean, Sanitized, and Separate from Everything Else

Your potable water hose must stay clean; otherwise, you could introduce pathogens into your RV water system. Store your water hose in a compartment separate from items that could contaminate it, especially your sewer hose!

Also, don’t let your fresh water hose lie on the ground. We always connect the male end to the female end to keep the hose sealed up when not in use.

Finally, periodically sanitize your hose by diluting bleach in a tub of water and submerging the hose for about 10 minutes. Rinse it immediately with cold water.

Know the Quality of the Water You Fill Up With

Sometimes you won’t know the quality of water you’re using, so using an inline water filter is critical. If you fill your fresh water tank at home, then you know the quality of the water going into your tank. (As an aside, keep in mind that a full fresh water tank adds a lot of weight to your RV which can impact fuel mileage.)

You can also research city water reports in the area where you’re staying. If an RV park uses a municipal water source, you may find an online report revealing the water quality. Based on these reports you can decide if the water is safe to use. But an inline filter is never a bad idea, especially if you intend to drink the water.

How Often to Sanitize RV Fresh Water Tank

A clean fresh water tank yields cleaner water

Clean water from your fresh water tank is essential for drinking, cooking, washing dishes, bathing, brushing teeth and watering pets.

We suggest that sanitizing your RV fresh water tank every six months is a good rule of thumb. This is especially important if you’re unsure of the quality of a water source you’ve connected to. If you’re on the road constantly and use your tanks often, you might want to do it more frequently.

But the same increase in frequency might be called for when letting water sit without use for long periods of time. And always sanitize your fresh water tank when you take your RV out of storage.

To summarize, how long to keep fresh water in your RV tank depends on several factors. Long story short: Don’t hold water in your tank for extended periods without using it. Keeping a clean tank is essential, as your health may depend on it!

The Ultimate Protection For Safe RV Drinking Water

If you really want to make sure the water on your RV is safe to drink, you can do the same thing we do — install an Acuva! LED water sanitization is used by major municipal water systems all over the world. Acuva’s system miniaturizes that technology for RV use.

Check out our videos about installing and testing our Acuva unit. You can even save 10% on the purchase of any Acuva for your own RV!

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DAVE

Sunday 14th of March 2021

I would not recommend using an inline water filter when filling your fresh water storage tank. Most of them remove chlorine. If you do wish to use a filter (to remove particulates), you must add chlorine to your storage tank. Not at the amount used for sanitation, but at an amount suggested to make water drinking safe. There are different formulas for city / well / stream water. Non-chlorinated water (especially in warm weather) is a breeding ground for unhealthy stuff.

Gene wengert

Sunday 14th of March 2021

Did you know that "splashless" bleach does not have the word "sanitize" on the label? Only the old fashioned bleach does. So, do not use splashless for sanitizing water tanks and pipes.

Mark Egland

Saturday 13th of March 2021

Thanks for the great article. When draining your fresh water tank where do you typically drain the water? I have a valve that I can open and drain to the ground, but that's a lot of water. Is there way to to divert that to a sewer outlet (other than running the fresh water into the gray tank)?

TheRVgeeks

Sunday 14th of March 2021

Hi Mark! Because the concentration of bleach is so low, we normally open the low point drain and allow it to run onto the ground. Alternately, as you mentioned, you can run the water pump and pump it into the sewer outlet via the gray tank, with the gray valve open of course. The only other way we can think of to get the water from the fresh tank directly to the sewer would be to affix an appropriately sized hose to the low point drain outlet of the fresh tank, and run it over to the sewer outlet, which is certainly a viable option. it might require something as inelegant as duct tape to hold it in place, but that would probably work just fine.

Joanie

Saturday 13th of March 2021

Hi & thank you for another great teaching article as always! I look forward to your videos & daily email articles.

Has anyone added colloidial silver to their tanks? I regularly make my own; so the cost of adding it to so many things is very inexpensive. From the glass of water which keeps my toothbrush disinfected & not exposed to air; from my toilet bowl brush to my diffuser; which sanitizes the air. (I used my diffuser in my rv bathroom to eliminate odors; since odors are bacteria & germs) I deal with fungus & black mold issues from previously living in florida & it is in my bloodstream & so using colloidial silver has become as routine to me as taking my daily vitamins; to keep those pathegens, fungus & mold from affecting my life more than it already has, these last 10 yrs. Colloidial Silver is a God-send.

TheRVgeeks

Saturday 13th of March 2021

Hi Joanie. Thanks for the kind words. We'll be interested to see if anyone else has any experience using colloidal silver to protect/sanitize their tanks. We haven't heard of using it that way, but have heard/seen a lot about its various benefits. So sorry to hear about your exposure to fungus/mold.

John Goodell

Friday 12th of March 2021

I think you should have mentioned city water vs well water. I guess you can cite several examples of bad city water (i.e. Flint, MI), but generally it is good quality and has been treated and tested. That treatment will assure the water stays fresher longer. Well water can be marginal, as in small amounts of coliform bacteria. I would never keep well water in my FW tank.

TheRVgeeks

Friday 12th of March 2021

Very true John, but in case you missed the mention about well water in the article, it's not too far from the top:

"If you filled your freshwater tank with water from non-municipal sources (think well water), as many of us do, these issues are more likely to develop. The water can become unfit to drink, cook with or shower in, depending on conditions (heat, for example) and how clean you keep your tank."

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