In this blog, we answer some of the pressing questions regarding CO2 cylinders and their use with sparkling water appliances.

What Does the Weight on a CO2 Cylinder Refer To?

When discussing a COcylinder's weight, it generally pertains to the weight of the carbon dioxide gas it contains, excluding the weight of the cylinder or container. For instance, if a CO2 cylinder is marked as weighing 2.6 kilograms, this figure only represents the gas's weight and doesn't include the cylinder's weight. In practice, the total weight of the filled cylinder, including the container, is typically much higher, often around 10 kilograms or more.

How to Compare the Amount of CO2 in a Bottle

Weight is the most reliable quantity to use for estimating the amount of CO2 in a container. Regardless of the external variables—such as temperature, changes in bottle pressure, or the gaseous or liquid condition of the CO2—weight stays a constant and steady parameter. The weight of the CO2-filled container will not change based on the surrounding environment or the condition of the gas inside.

In contrast, because CO2 can vary greatly based on variations in temperature and pressure, measuring it in litres (volume) is less accurate. Volume measurements can be inaccurate because gas volumes increase or contract in response to changes in pressure and temperature. Consequently, weight is the recommended method for accurate quantification since it offers a more reliable and consistent estimate of the real amount of CO2 within a bottle.

CO2 Bottle Comparison Table

Bottle Size



Sparkling Water Produced

2.6KG (Refillable)

4 Litres


Approx. 430 Litres

1.1KG (Disposable)

2.2 Litres


Approx. 180 Litres

You will notice that the Refillable 2.6KG cylinders have 82% more volume, but 136% more CO2 by weight compared with the 1.1KG disposable cylinders. This is because the CO2 is compressed at a higher pressure in the refillable cylinders which fits more total gas in.

Are CO2 Cylinders Measured by Volume or Weight?

Most CO2 cylinders have both volume and weight measurements. Although weight is the most precise way to calculate the amount of CO2 in a bottle, manufacturers often include the volume of the cylinder (often measured in litres) as an extra detail.

To give an example, the volume of water in a CO2 bottle would match the volume measurement on the cylinder if the bottle were filled to the brim with water. This implies that the cylinder would hold precisely 5 litres of water if it were marked with a specific volume, say 5 litres, and you were to fill it up to the brim. It's crucial to remember that this volume measurement pertains to water and not the actual volume of CO2 that the cylinder may contain because the two materials have distinct densities and spatial requirements. Consequently, weight continues to be the more precise and trustworthy metric for determining the amount of CO2 in the cylinder.

Interesting Facts About Carbon Dioxide (CO2)

  • Natural Component: CO2 is a naturally occurring gas and a vital part of Earth's carbon cycle. It is released into the atmosphere through natural processes like respiration and volcanic eruptions.
  • Physical State in Cylinders: CO2 exhibits an intriguing state when kept in compressed gas cylinders, such the ones used to carbonate sparkling water gadgets. It is compressed to a high pressure inside the cylinder, which results in a partly liquid layer at the bottom and a gaseous layer at the top of the container. CO2 cylinders must be positioned upright when connected to your sparkling water appliance because of this dual condition.
  • Dry Ice: When CO2 is compressed and cooled, it turns into dry ice, a solid form of carbon dioxide. Dry ice is often used for cooling and special effects due to its ability to sublimate (change directly from a solid to a gas).
  • Tasteless, Colourless, and Odourless: Carbon dioxide is a fully flavourless, odourless gas that occurs naturally. Because of its invisibility and lack of sensory characteristics, people find it difficult to detect it without specialised equipment.
  • Non-Flammable and Fire Extinguishers: CO2 does not assist combustion because it is non-flammable. Owing to this characteristic, CO2 is frequently utilised as an extinguishing agent in fire extinguishers. When released, CO2 absorbs oxygen from the surrounding air and smothers the fire by lowering the amount of oxygen that may burn.

Here at Aquastream, we provide a user-friendly online ordering experience, personal service, and a comprehensive range of quality CO2 products.

Check out our range of Sparkling Carbon Dioxide to suit brands such as ZIP, Puretec and Billi.