Cold Brew Keg Systems: What They Do and What to Look For

What a system consists of

• Corny keg — a stainless pressure vessel, 5 or 9 litres, ball-lock or pin-lock. Ex-soft-drink kegs are common and inexpensive.
• Regulator — dual gauge, showing cylinder contents and delivery pressure.
• Gas — nitrogen or beer gas for nitro; nothing at all if you dispense by gravity.
• Faucet and lines — a stout faucet with a restrictor plate if you want the cascade.
• Refrigeration — cold brew is a fresh product and must stay cold.

Gravity, pressure, or nitro

Gravity needs no gas. Simplest, cheapest, and the coffee oxidises as air replaces what you draw off.

Pressure dispense with a small nitrogen head pushes coffee out while keeping air away, which meaningfully extends life.

Nitro adds the restrictor plate and a higher pressure, producing the cascade and creamy head. Use nitrogen, not CO2 — CO2 dissolves readily and forms carbonic acid, which makes the coffee taste sharp and fizzy rather than smooth.

Filtration is not optional

Fine particles clog the restrictor plate in a stout faucet, and a clogged faucet is a genuinely tedious thing to clear. Filter the concentrate properly before it goes near a keg: a paper filter or a fine cloth after the initial screen.

Cleaning is the whole job

Coffee in a keg is a nutrient-rich liquid sitting at fridge temperature. That is a growth medium.

Break the system down and clean it between batches, not between months. Disassemble the faucet — restrictor plates hide residue. Replace keg lid and post O-rings when they harden. Sanitise after cleaning, and rinse lines through rather than merely flushing water past them.

Safety

Fit a regulator between cylinder and keg, always. Cylinder pressure will rupture a keg if applied directly. Secure cylinders upright, keep the space ventilated since nitrogen displaces oxygen silently, and verify the pressure relief valve works before each use.

The honest verdict

If you drink several cold brews daily through summer, a keg is a real convenience and keeps the coffee better than a jug. For a couple of glasses a week, a sealed bottle in the fridge does the same job with none of the cleaning.