When determining how much water you and your family, or maybe even your animals, will need for a given period of time either when packing for a trip or expedition, or preparing for disaster, gallons is the most commonly used figure.
Therefore, it is helpful to calculate your on-hand water storage accordingly.
One way to make your planning a little easier is to figure out how many gallons of water there are in a typical case of bottled water. For instance, how many gallons are there in a 24 pack of bottled water?
There are approximately 3.16 gallons of water in a typical case of bottled water consisting of standard 16.9 oz bottles. The actual measure of gallons may vary if the volume of the bottles is larger or smaller.
Easy enough. If you want to make your planning simple and leave yourself a margin of error or a little extra, just call it three gallons, or you can be slightly more accurate without making the math a nightmare by calling it three and a quarter gallons.
That’s pretty much all there is to it, but we have some more information for you below if you read on.
Volumes Vary by Brand and Pack
The first thing you should know is that the above answer is only valid for a case of water containing the standard 16.9 oz bottles that you see everywhere.
The volume of a case of water can vary depending on the brand and the size of the bottles in each case.
For example, some 24 packs of water might contain smaller 8 oz bottles while others might have larger 20 oz bottles, in which case you’ll have 1 1/2 gallons in a case or 3 3/4 gallons, respectively.
Bottled Water Evaporates Slowly Over Time
The second thing to keep in mind is that the bottles you have on hand might not actually have 16.9 ounces in them. Not anymore.
Even if you never open a bottle of water, over time the water will gradually evaporate out of the bottle and into the air. This is called closed container loss (if not actual leakage) and it’s a real thing.
The industry standard for bottled water is that by the expiration date, which is generally two years from bottling, each 16.9 oz bottle will have lost no more than 3.38% of its original volume.
This means that each bottle you have will actually have about 16.4 ounces in it by the time two years has passed.
So, if you do the math, a 24 pack of water that is two years old will only have about 2.96 gallons in it, not the 3.16 gallons when first bottled.
This loss isn’t much, but if you are planning for long-term water storage or filtration and need to know exactly how many gallons you have on hand, it’s something to keep in mind.
The Equation for Determining Gallons from Ounces
Calculating the actual gallons of water on hand from a known quantity in ounces is a simple equation. Just divide the number of ounces by 128 (128 is the number of ounces in a gallon).
So, for example, if you have 10 bottles that each have 16.9 ounces of water in them, you would have 10 x 16.9 / 128 = 1.3 gallons of water total.
You can do the reverse, too: if you want to know how many ounces of water you have in a given number of gallons, just multiply the number of gallons by 128. So 3 gallons = 3 x 128 = 384 ounces.
As you can see, it’s not difficult to determine how many gallons are in a 24 pack of water, or any other amount for that matter.
Just remember that the specific size and, possibly, age of your bottles will affect the actual volume of water, so plan accordingly.
More Useful Info: Water Weight
When you are planning to pack or store water, especially for long-term storage, it’s important to know not only how many gallons you have on hand, but also how much water weighs. This is helpful for a number of reasons.
For example, if you need to transport a large quantity of water, you’ll need to know how much your vehicle can safely carry, and how much a person can be expected to haul, and for how far.
Water is quite heavy, weighing in at 8.34 pounds per gallon. So, the 24 pack of water in question weighs about 26.35 pounds (3.14 gallons x 8.34 pounds per gallon).
It is a figure you should keep in mind when stacking bottled water to the ceiling in a closet or installing tanking anywhere in or near your home; you can quickly reach unsafe weight loads that might cause structural damage or, worse, injure someone.
Tom has lived and worked on farms and homesteads from the Carolinas to Kentucky and beyond. He is passionate about helping people prepare for tough times by embracing lifestyles of self-sufficiency.