Bar Tools

Soda Siphon

A soda siphon is a refillable pressurised bottle, usually holding about a litre, that carbonates cold water with a CO2 charger and pours it through a valve. It makes fresh soda water on demand and holds its pressure between pours. It serves any drink topped with soda, from the Tom Collins to the Campari and Soda.

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The tool

About the Soda Siphon

Cold Water Takes the Gas

A charger holds about 8g of CO2 under pressure. When it is screwed into the head, the gas fills the bottle and dissolves into the water.

Cold water holds far more dissolved CO2 than warm water at the same pressure, so the temperature of the water sets how lively the soda will be. Fill from the fridge, charge, give it a brief shake and let it rest in the fridge before the first pour.

A Charged Siphon Is a Pressure Vessel

Most of the safety rules follow from that. Use only CO2 chargers made for soda siphons, in the size the maker specifies, usually one 8g charger per litre.

Fill only to the maker's line, so there is space for the gas. Our rules: never add a second charger unless the maker’s instructions allow it, never leave a charged siphon in the sun or near heat, and always let out the remaining gas through the lever before you unscrew the head.

Check old glass siphons before use. A chip or crack weakens the glass under pressure, so retire a damaged one, however handsome it is.

Keep chargers away from children, and never inhale the gas from any charger.

Fresh Soda Beats an Opened Bottle on Fizz

The case for a siphon is freshness. In our experience an opened bottle of soda loses its fizz within a day or two, and much of it is poured away; a siphon holds its pressure, so the last pour is like the first. That suits drinks topped with soda, like the Tom Collins and the Campari and Soda.

Bottled soda keeps one advantage: added minerals, which give it a faint salty roundness. A small pinch of bicarbonate of soda in the siphon brings plain carbonated water closer to it.

Ways to get soda water for a drink

Soda siphon

Fizz: Lively when fresh; set by water temperature
Keeps once opened: Days to weeks while sealed
Suits: Regular soda drinks at home

Large bottle of soda

Fizz: Consistent
Keeps once opened: A day or two
Suits: Occasional drinks; mineral taste

Countertop carbonator

Fizz: Adjustable
Keeps once opened: As a sealed bottle
Suits: Large amounts of plain sparkling water

Small cans or bottles

Fizz: Consistent
Keeps once opened: Single use, no waste
Suits: One drink at a time

Option	Fizz	Keeps once opened	Suits
Soda siphon	Lively when fresh; set by water temperature	Days to weeks while sealed	Regular soda drinks at home
Large bottle of soda	Consistent	A day or two	Occasional drinks; mineral taste
Countertop carbonator	Adjustable	As a sealed bottle	Large amounts of plain sparkling water
Small cans or bottles	Consistent	Single use, no waste	One drink at a time

The Washers Wear First

When a head washer hardens, the siphon hisses after charging and the soda comes out weak. Replace the washer rather than adding another charger.

Rinse the head and the tube in warm water after use. Use the siphon for water only unless the maker says otherwise; sugar and pulp in the valve make it stick and dribble.

Using it

Using the Soda Siphon

Usage

Topping soda-lengthened drinks, such as collinses, the Gin Sling, the Americano and the Campari and Soda, with freshly carbonated water. A siphon also spares you a half-used bottle of soda going flat in the fridge.

Pro Tip

We keep a second bottle of water in the fridge. When the siphon runs dry, the next litre is already cold, and the new charge dissolves properly.

Professional Tips

Fill with water straight from the fridge, up to the maker's line and no further.
Charge once, shake briefly, then let it rest cold before pouring.
Hold the siphon upright and press the lever gently.
Let the soda run down the side of a tilted glass.

Alternatives

Budget Alternative

A plain aluminium siphon used with the chargers its maker specifies does the job. Buy one whose spare washers are still sold, since the washers wear first.

Premium Option

A heavy stainless steel siphon, or a restored vintage glass one with new washers. The soda is the same; the money buys durability or looks.

Specifications

Material
Stainless steel or aluminium; older and decorative models in glass, often wrapped in mesh
Capacity
About one litre in the ones we use; half-litre models are made
Details
Screw-on head with valve, lever and charger holder; takes CO2 chargers, usually one 8g charger per litre

Go further

More to explore

Common Questions

How does a soda siphon work?

A charger holds CO2 under pressure. Screwed into the head, it is pierced and the gas fills the sealed bottle, where some of it dissolves into the water. The lever opens a valve, and the pressure inside pushes soda up the tube and out of the spout.

Is a soda siphon safe?

Yes, used as the maker intends. Use only CO2 chargers made for soda siphons, one per fill unless the instructions say otherwise. Never fill past the line, never heat a charged siphon, and release the gas before unscrewing the head. Our rule is that a glass siphon with a crack or chip is never pressurised again.

Is siphon soda better than bottled?

It is fresher. A siphon holds its pressure between pours, so the last glass is as lively as the first, while in our experience an opened bottle goes flat within a day or two. Bottled sodas often have added minerals that a siphon of tap water lacks, so the taste can differ.

What does soda water do when added to spirits?

It lengthens and chills the drink without adding sugar. The bubbles carry aroma up from the glass, and dissolved CO2 forms a little carbonic acid, which gives the drink a slight sharpness. Added minerals in some sodas make it taste a touch rounder than plain sparkling water.

How long does a charge last?

While the siphon stays sealed, the pressure holds for days or weeks. Each pour lets out a little gas, so a siphon used daily fades over a week or two. Most litre siphons take one 8g charger per fill; recharge when you refill with fresh cold water.

Can I use a cream charger in a soda siphon?

No. Cream chargers hold nitrous oxide, which is for whipping cream and does not make soda water. Use the CO2 chargers made for your siphon. Never inhale the gas from any charger; nitrous oxide has been a Class C drug in the UK since 8 November 2023, by the Home Office’s guidance.

What is the difference between soda water and sparkling water?

Soda water usually has added minerals, often sodium bicarbonate, which give it a faint saltiness. Sparkling mineral water takes its taste from its source. A siphon filled from the tap makes plain carbonated water; a small pinch of bicarbonate of soda in the bottle brings it closer to soda water.

Why is my siphon soda flat?

Usually the water was not cold enough, the bottle was overfilled, or the head washer is worn and the gas is leaking. Chill the water first, fill only to the line, and listen for a hiss after charging. If it hisses, replace the washer before charging again.

Sources.

Checked between 18 October and 19 October 2026.

Google Patents, “US patent 4,694,975, Method and apparatus for storing and dispensing fluids containered under gas pressure (background)” (patent background: Deleuze and Dutillet’s French patent of 1829 for a siphon champenois; Perpigna’s patent of 1837 the forerunner of the present-day siphon seltzer bottle).
Home Office, GOV.UK, “Nitrous oxide ban” (Class C from 8 November 2023).

Make something

Made with the Soda Siphon

Used In These Cocktails

Campari & Soda Tom Collins Gin Sling Americano Doctor Funk

Related Equipment

Related Ingredients

Soda Water

Guide by Jerry Can Spirits · Updated 19 October 2026

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