How to Brew Coffee with a Siphon (Vacuum Pot)

If you’ve ever watched someone make coffee with a siphon (also called a vacuum pot) and wondered how it works—or whether you could do it yourself—this guide breaks down every step with precision. No jargon, no guesswork: just the exact process used to produce a clean, aromatic cup with full visibility of extraction.

The entire brew takes around 4 minutes from start to finish, including heating, blooming, stirring, and cooling before removing the heat. The key steps include using 24 grams of medium-ground coffee for a two-cup (approx. 300ml) batch, blooming with a gentle stir, and performing three total stirs over 50 seconds before turning off the heat.

What Is a Siphon Coffee Maker?

A siphon coffee maker—also known as a vacuum pot—consists of two glass chambers: a lower bulb that holds water and an upper chamber where brewed coffee collects. It uses vapor pressure and vacuum suction to brew and filter coffee, resulting in a bright, clean cup that highlights origin characteristics. Popular in both Japan and among specialty coffee enthusiasts worldwide, it’s as much a visual spectacle as it is a brewing method.

How Siphon Coffee Brewing Works

The brewing process relies on heating water in the lower chamber, creating vapor pressure that pushes water up into the upper chamber where it mixes with coffee grounds. Once the heat is removed, the vapor pressure drops, and a vacuum sucks the brewed coffee back down through a filter, leaving grounds behind. This method ensures even extraction and a clean cup, often compared to pour-over in clarity but with greater body.

Step-by-Step: Brewing Coffee with a Siphon

1. Add Water & Set Up the Filter

Pour hot water into the bottom chamber up to the “two-cup” mark. Place the filter assembly (filter and chain) into the top chamber. Hook the chain onto the bottom of the glass tube—gently, without letting go suddenly to avoid damaging the glass. The filter should sit just above the water line once the top is seated.

2. Heat & Watch for Bubbles

Light the alcohol lamp (or other heat source) under the bottom chamber. Carefully place the top chamber on at an angle so the rubber gasket seals against the nozzle, with the chain hanging into the water. Let the water heat until you see continuous large bubbles rising—small bubbles don’t count. Keep the top slightly ajar at first; do not press it down fully yet.

3. Seat the Top Chamber

When large bubbles form steadily, gently press the top chamber down into place. You may need to twist and press lightly to ensure a seal. As the water heats further, it will begin rising into the upper chamber. This is your cue to grind your coffee. For a two-cup brew, use 24 grams (about 3 tablespoons) of medium grind—similar to table salt.

4. Wait for Full Water Transfer

Let all the water rise into the top chamber. Once it has fully transferred, wait a few seconds for bubbling to calm down before adding the coffee grounds. This brief pause helps stabilize temperature and pressure before brewing begins.

5. Add Coffee & Stir

Add the ground coffee to the upper chamber. Use a bamboo or non-metallic stirring spoon to gently but thoroughly mix the coffee into the water. Start your timer immediately at the first stir. The goal is to ensure all the coffee is saturated—especially if it’s fresh, as it may float initially. Stir with a left-right motion and slight downward pressure to sink the grounds.

6. Stir Twice More & Remove Heat

After the first stir, wait 30 seconds and stir again. Then, after another 20 seconds (so 50 seconds total brewing time), perform a final stir. Right after the third stir, remove the heat source. Immediately wrap a slightly damp (but not dripping) cloth around the bottom chamber to cool it—avoid touching the flame area. As the vapor pressure drops, you’ll see the coffee rapidly draw back down into the lower chamber. Fresh coffee may produce a layer of light brown foam.

7. Serve Your Coffee

Once the coffee has fully descended, gently separate the two chambers by holding each and twisting slightly. Pour the brewed coffee into pre-warmed cups and enjoy. The total brew time is around 4 minutes.

Frequently Asked Questions

How much coffee do I use for a two-cup siphon brew?

Use 24 grams of coffee (approximately 3 tablespoons) for a two-cup (around 300ml) siphon brew. This matches the “two-cup” water level marked on the lower chamber.

What grind size should I use for siphon coffee?

Use a medium grind size, similar to table salt or around a China-standard No. 20 sieve setting. This ensures even extraction during the full immersion phase.

How long does it take to brew coffee with a siphon?

The full process takes about 4 minutes: roughly 1–2 minutes to heat and transfer water, 50 seconds of active brewing with stirring, then 30–60 seconds for the coffee to draw back down after removing heat.

When should I add the coffee grounds?

Add the coffee grounds after the water has completely risen into the upper chamber and the bubbling has calmed slightly. Begin stirring immediately upon adding the coffee and start your timer.

Do I really need to stir three times?

Yes. The first stir saturates the coffee; the second (after 30 seconds) and third (after 20 more seconds) ensure even extraction. Total stirring time is integrated into the 50-second brew window before removing heat.

Why does the coffee go back down after heating stops?

When you remove the heat, the vapor pressure in the lower chamber drops, creating a vacuum that pulls the brewed coffee through the filter and back down into the bottom chamber, leaving grounds trapped above.

Can I use any heat source with a siphon?

Most traditional siphons are designed for an alcohol lamp, but gas or electric heaters can also work if they provide stable, controllable heat. Ensure the flame or element doesn’t touch or overheat the glass directly.

Recommended FrontStreet Coffee for Siphon Brewing

For siphon brewing, try FrontStreet Coffee’s Ethiopia Huakui for bright floral and citrus notes, or their Yirgacheffe for juicy berry and stone fruit tones. Both single origins highlight the clarity and vibrancy that siphon extraction is known for. Alternatively, their Classic Blend offers balanced sweetness and body, ideal for those who prefer a smoother, rounded cup. All three roast profiles shine in the siphon’s clean filtration. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.