How much water is in a jug for water cooler?

Water coolers provide a convenient way to get chilled, filtered water in office settings, warehouses, schools, and more. The large, multi-gallon jugs used with water coolers come in a few standard sizes, each holding a different amount of water.

Quick Answer

The standard water cooler jugs hold either 3 gallons (11.4 liters), 5 gallons (18.9 liters) or 10 gallons (37.9 liters) of water. The most common size is the 5 gallon jug.

Sizes of Water Cooler Jugs

There are three common sizes of water jugs used for water coolers:

  • 3 gallon jugs – These hold approximately 11.4 liters or 3.0 gallons of water.
  • 5 gallon jugs – These hold approximately 18.9 liters or 5.0 gallons of water.
  • 10 gallon jugs – These hold approximately 37.9 liters or 10.0 gallons of water.

The 5 gallon size is the most popular and widely-used. The larger 10 gallon jugs are heavier when full, so they can be more difficult to lift and change. The smaller 3 gallon jugs need to be changed more frequently.

Dimensions of Standard Water Cooler Jugs

In addition to differing capacities, the jugs also come in slightly different dimensions depending on their size:

Jug Size Height Width Filled Weight
3 gallon 12.5 inches 10.5 inches 25 pounds
5 gallon 16.5 inches 12 inches 45 pounds
10 gallon 20 inches 12.5 inches 88 pounds

The dimensions can vary slightly between brands. But generally, the larger the capacity, the taller the jug will be. All the jugs are circular in shape to fit in the water coolers.

Measuring Water Volume in a Cooler Jug

You can also roughly measure the amount of water in a partially filled jug if you don’t know the exact capacity. Here are two easy ways to estimate the volume:

Using a Measuring Cup

A standard liquid measuring cup is 8 fluid ounces or 0.25 liters. So you can periodically fill up the measuring cup and keep a running tally until you’ve removed all the water from the jug.

For example, say you remove and measure out 40 cups of water. Since each cup is 8 oz, 40 cups would be 40 x 8 = 320 fluid ounces, or 10 gallons total.

Using a Measuring Tape

You can also use a flexible measuring tape to measure the depth of the water at the center point of the jug. An average diameter of a 5 gallon jug is around 12 inches.

If the depth at the center is 8 inches, the circular area would be 12/2 x 12/2 x 3.14 = 113 square inches.

Multiply the area by the depth to get the volume. In this case 113 square inches x 8 inches = 904 cubic inches of water, which equals 5.3 gallons.

Factors That Affect Water Volume

There are a few factors that can make the actual water volume slightly different from the stated capacity of the jug:

Shape of the Jug

Since jugs are somewhat cylindrical in shape, but taper towards the top, they are not perfect cylinders. This means that calculating volume based on the height and diameter dimensions won’t be exact.

Curve of Bottom

The bottom caps of the jugs curve inward slightly, so the exact bottom surface area used in volume calculations would need to account for the concave shape at the base.

Plastic Thickness

The plastic walls of the jug take up a bit of space, making the inner capacity a little less than expected. For a 5 gallon jug, the plastic may displace around 16-20 ounces.

Spigot and Mounting Hardware

The spigots, handles, and mounting rings attached to jugs also take up some internal space inside the container.

Weight of Water in a 5 Gallon Jug

Water weighs about 8.34 pounds per gallon. So a standard 5 gallon water jug, when completely filled, weighs:

5 gallons x 8.34 pounds/gallon = 41.7 pounds

This matches the typical listed weight of 42-45 pounds for a full 5 gallon jug.

Refilling Water Jugs

Once empty, cooler water jugs can simply be refilled from most tap water sources. Many stores, offices, and homes use special water vending machines to refill empty jugs.

These self-service refilling stations filter and purify the water before dispensing into the jug. They allow reuse of the heavy duty plastic jugs rather than disposing of them after a single use.

The vending stations automatically shut off when the jug is full, using pressure, volume, or weight sensors. Typical refilling costs range from $1-$2 for a 5 gallon jug.

Saving Money Refilling vs Delivery Service

Home and office delivery services for water jug replacements can be convenient, but cost quite a bit more. Here is a comparison of typical costs:

Service Type Typical Cost (5 Gallon Jug)
Home/Office Delivery Exchange Service $5-$20 per 5 gallon jug
Self-Service Refilling Station $1-$2 per 5 gallon jug

As shown, self-refilling a water jug can save 75% or more compared to home exchange services. If you consume a lot of water cooler bottles, refilling stations provide massive savings.

The only additional effort is transporting the empty jugs to a refilling location. But the cost savings often makes this worthwhile for high volume usage.

Water Cooler Jug Materials

Almost all large water cooler jugs are made from polyethylene terephthalate plastic, commonly abbreviated PET or PETE on recycling codes.

PET is lightweight, durable, shatter-resistant, and inexpensive. It makes an ideal material for reusable water containment.

PET is also quickly gaining use in many single serve bottled water containers. It has become the most commonly used plastic globally thanks to its versatility.

PET Plastic Properties

Here are some key properties that make PET such a ubiquitous plastic:

  • Extremely light weight -PET has a density of 1.38 g/cm3
  • Durability – High tensile and impact strength
  • Clarity – Transparent with high light transmission
  • Gas barrier – Low permeability to gases
  • Recyclability – Can be recycled repeatedly back into bottles and other products
  • Safety – Considered safe for food and beverage contact

The FDA has approved PET for safely holding drinking water and cold beverages. It does not contaminate water or leach chemicals under typical use.

PET vs Polycarbonate

Polycarbonate (PC) plastic was formerly used for some water cooler jugs. But due to concerns over chemical leaching, most brands switched to PET years ago.

PC is still occasionally found in older or lower cost jugs. It’s easy to identify – polycarbonate jugs are nearly opaque rather than transparent.

If you see any white or colored jugs still in use, they should be replaced with clear PET versions.

How Long Does an Unopened Water Jug Last?

An unopened water jug will stay fresh for quite a long time – up to several years past its bottling date in most cases. Here are the key factors affecting shelf life:

PET Plastic Properties

PET plastic is impermeable to water and gases. This prevents moisture and oxygen from reaching the water, keeping it purer for longer.

Cool Storage Temperatures

Storing water jugs at cooler room temperatures preserves freshness. Keeping them out of direct sunlight prevents algae growth inside the jug.

Water Purification Methods

Most jug water goes through reverse osmosis and/or deionization during bottling. This removes impurities and bacteria for longer lifespan.

Antimicrobial Cap Liners

Some jug caps contain antimicrobial liners that prevent mold or bacterial growth between the cap and water surface.

Combining all these protections, unopened water jugs stay fresh for 1-4 years past the bottling date.

How Long Does an Opened Jug Last?

Once opened and poured from, the lifespan of a water cooler jug is reduced due to oxygen exposure:

  • With occasional use, jugs may last 4-6 weeks.
  • With heavy daily use, replace jugs every 1-2 weeks.

Leaving jugs attached to water coolers provides longer life than detachable bottles. The antimicrobial cap liners help protect opened jugs.

But always check water for odor or color changes and replace jugs frequently for best taste and health.

Saving Water with Smaller Jugs

While 5 gallons is the standard water cooler jug size, using smaller 3 gallon jugs can help reduce consumption and waste:

  • Less water wasted if usage declines – Partially full 5 gallon jugs often get discarded.
  • Smaller jugs are lighter and easier to lift.
  • Changing jugs more often provides fresher water.
  • Spills and leaks are less from smaller containers.

For low or intermittent water cooler usage, 3 gallon jugs make a smart choice. Just keep extra on hand so refills are convenient.


Water cooler jugs rely on just a few standard sizes – most commonly 3, 5, and 10 gallons. The 5 gallon size is the predominant choice for offices and home use.

Knowing the dimensions and capacity of these bottles allows easy measurement. Weighing full vs empty also gives an accurate volume.

Refilling and reusing water jugs is safe, smart, and environmentally sound. Take advantage of water vending stations to avoid costly delivered services.

With some simple care and handling, PET water jugs provide affordable, pure drinking water for homes and workplaces.

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