Friday, June 2, 2023


How long can fresh water be stored in the RV’s tank?

Dear Dave,
I was wondering how long I can store water in my 80-gallon fresh water tank. We went on a trip in early March of this year and I came home with roughly 3/4 tank of water. It is now the end of April. What are my options? Thanks, Dave. —Scott, 2023 Grand Design Solitude S class 5th wheel

Dear Scott,
In my opinion, it depends on the quality of water to start with, as most fresh water tanks are filled at the campground that typically are using well water that can have calcium, rust, lime, and other minerals. It is not treated like a municipal water plant or even a home softener. Campgrounds must certify their well water once a year and post an MSDS sheet. However, the well can get arsenic and contain bacteria and other contaminates between certifications. So, if you start with poor water quality, it will not take long before the water is bad.

Let’s say you do have a safe water source; how long can it be stored? If you search the internet, you will find dozens of so-called “experts” or “influencers” that mostly state 10 days to two weeks, without providing facts on how they arrived at that.

Six months

According to the CDC and FEMA, who I trust as knowledgeable and experts at storing fresh water for emergency purposes, you can store fresh water for up to six months as long as it is in a sealed container. Your fresh water tank is not completely sealed as it has a vent at the top. However, they are referring to a container that rodents, bugs, and other contaminants can’t get into. That means your fresh water tank would comply with their recommendation.

Testing the water

There are a few tests that you can perform to determine the water quality in your tank. You can with a simple digital tester that will determine the parts per million, such as the Total Dissolved Solids (TDS) Tester, which is available here.

Just pour some of the water into a cup and immerse the probes in and it will give a reading of the quality of the water.

If you want to test further, you can use the Safe Home well water test kit, which has 14 different tests and is available on Amazon here.

How are you using the water?

I don’t drink the water that is stored in the fresh water tank as it typically gets a plastic taste almost immediately. I realize six months is probably a little long when it comes to an RV, especially when temperatures rise to higher levels and the water can almost boil inside the tank. Before you start throwing comments, I know that the boiling point is 212 degrees and it would never get that hot! I said almost.

The CDC and FEMA recommend storing water in a temperature range of 50-70 degrees F. Certain chemicals found in plastics can leach into the water and will do so more rapidly at higher temperatures. My point is, if you are just using the water in the fresh water tank to shower, flush the toilet, clean dishes and such, a plastic taste is not that bad. But keep in mind, poor quality well water can show safe on the tests, but can get a little skunky after a short amount of time, especially if you don’t start with a clean tank. I think it’s also a good idea to clean the tank out every spring with the Thetford Fresh Water Tank Cleaning Kit.

What are your options?

As stated earlier, you can test the water with the various testers. I believe it will be good for at least a couple of months, or drain the water and wait to refill on your next trip. I typically do not fill the tank much before starting off as I don’t want the 8.6 lbs. per gallon sloshing around and adding weight. If you do decide to drain the tank, I would suggest finding a way to capture the water to use for watering plants, trees, or other items so you are not wasting it.

 You might also enjoy this from Dave 

Can I sanitize RV’s fresh water tank without running solution through water lines?

Dear Dave,
My coach is fully winterized as I flushed the pink, nontoxic, antifreeze through all lines, and the fresh water tank has been drained. I am about to dewinterize the coach and I will want to sanitize, with a bleach solution, the fresh water system. Given that there has been antifreeze in the lines for several months, do I still need to run the bleach solution in all the pipes? It sure would be easier if I only had to allow the bleach solution to sit in the fresh water tank, drain it after a few hours, and not flush the bleach solution through the pipes. Thank you for your advice and for what you do! —Philip, 2022 Newmar Dutch Star 4081

Read Dave’s answer.

Read more from Dave here


We have a popular forum for Ask Dave. Please be as brief as possible. Attach a photo or two if it might help Dave with his response. Click to visit Dave’s forum. Or send your inquiries to him using the form below.

Click or drag a file to this area to upload.


Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.


4.8 9 votes
Article Rating
Subscribe to comments
Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Inline Feedbacks
View all comments
Jay Ward
28 days ago

We usually carry about 15 gallons of fresh, city water in our tank just to use on the road for potty and hand washing. It’s filtered on board and we also use a Clearsource Ultra triple filter in campgrounds. Drinking water is bottled. As we use the water on board we top it up to 15 gallons or so. If we were to put water in the tank from a campground it would always go through the Clearsource.

29 days ago

…and never fill your water tank at an RV Park that has the word “Sulphur”in its name.

Thomas D
29 days ago

In the TDS chart, the second list down says safe water and source of RO ,Mountain Sprongs. What is a Sprong? I can’t believe they’d let a typo like that go!
Anyway, we carry enough water to flush toilet and not much more. Weight you know.
Water for camper gets a 2stage filter at the campground and we drink bottled water.

David Solberg
29 days ago
Reply to  Thomas D

Must be if there are more than two springs in the area, it’s “sprongs”?

Tommy Molnar
29 days ago

One thing we ALWAYS do is run with our fresh tank full. It gives me a bit more peace of mind in windy conditions to have more weight on board our trailer, and it lowers our center of gravity. At least that’s what I tell myself . . .

Edward Wullschleger
29 days ago
Reply to  Tommy Molnar

Same here about the weight. Our trailer is only 3100 lbs, empty, and I’ve upgraded to D tires, so a little more weight actually feels safer, especially when there’s any wind.

I also prefer drinking the tap water I’ve had in various parts of Colorado more so than any bottled water that I’ve experienced. Plus, I’ve never had problems with any tap water from municipal supplies anywhere I’ve lived or visited in the U.S. in the past. I don’t understand why people are so afraid of their water in most places in this country. Of course, I’ve read the same stories as others about a few exceptions where the water had lead or other dangerous substances, but they truly are the exception.

Edward Wullschleger
29 days ago

I do empty the water at the end of each trip and refill at the start of the next.

Tommy Molnar
29 days ago

I totally agree about drinking municipal water. Not sure how the big scare got started. Kinda like when the ‘pandemic’ got started and all of a sudden everyone was stocking up on TP and bottled water. People are funny . . .

29 days ago

Usually not much in the fresh water tank when we are on the road. Just enough to flush the toilet a few times and wash our hands. We carry drinking water in used milk jugs because we know it is good. I guess it would be different if we boondocked.

29 days ago

We never use fresh water contained water to provide for human or pet consumption. Always use bottled water. Nothing worse than a sick animal or human.

Jesse Crouse
29 days ago

From a Plumber. Easy is not always safe. I sanitize to dewinterize and dump all water 2 or 3 times through out the season.

Sign up for the

RVtravel Newsletter

Sign up and receive 3 FREE RV Checklists: Set-Up, Take-Down and Packing List.