Soda Siphon

Usage

Soda water for Highballs, Collinses, Fizzes and Spritzes, and any drink where the carbonation is the last thing added. Also for charging citrus juice or tea to make a sharper, more aromatic mixer than plain soda.

How It Carbonates

A charger holds around 8g of liquid CO₂ under pressure. Screwing it into the head punctures the seal and releases the gas into the sealed bottle, where it dissolves into the water.

The amount that dissolves depends almost entirely on temperature and pressure. Cold water holds several times more CO₂ than warm water at the same pressure, which is why chilling before charging is not optional. A siphon filled from a warm tap produces something noticeably flatter than one filled from a fridge.

Shaking or inverting a couple of times after charging speeds the gas into solution. Leave it a minute before pouring and the result is genuinely sharp.

Against Bottled

A fresh siphon charge produces a higher level of carbonation than most bottled soda, and it arrives with more aggressive, larger bubbles that survive being poured over ice.

The bigger advantage is that it does not go flat. A bottle of soda opened for one gin and tonic is measurably duller by the next day and useless by the weekend, so most of it gets poured away. A siphon holds pressure between uses and the last glass is as lively as the first.

Against that: premium bottled sodas are made with mineral compositions chosen to suit particular spirits, which tap water and a charger cannot imitate.

Soda Against Sparkling Water

They are different things and the distinction matters in a drink.

Soda water has added minerals, usually sodium bicarbonate and sometimes potassium, which give it a faintly saline, slightly rounded taste. That salinity is why a Tom Collins made with soda tastes fuller than the same drink made with plain carbonated water.

Sparkling mineral water is naturally carbonated or naturally mineralised spring water, and its character depends on its source. Plain carbonated water is exactly that: water with gas and nothing else.

A siphon makes the third of these by default. A pinch of bicarbonate in the bottle turns it into the first.

Charges and Care

One 8g charger carbonates a litre. The pressure holds for weeks in a sealed siphon, so a charge lasts as long as the water does rather than expiring on a timer, though each dispense releases a little gas, and a siphon poured from daily will fade over a fortnight.

Use CO₂ chargers, never N₂O ones. They are not interchangeable: nitrous oxide is for whipping cream and does not dissolve into water the same way.

Rinse the head under warm water and dry it after every use. Sugar or juice residue in the valve is what makes a siphon jam or dribble, and the internal tube needs occasional cleaning with a bottle brush.

What to Look For

• A serviceable head with replaceable washers
• Standard 8g CO2 bulb fitting
• A litre body you can fridge-fit
• Steel over aluminium for the decades

Professional Tips

• Chill the water first. Cold water absorbs far more CO₂.
• Charge, then rest it for a minute before dispensing.
• Dispense down the inside of a tilted glass.
• Rinse and dry the head after every use, or it sticks.

Specifications