Brewing Coffee With A Chemex: A Step-By-Step Guide

Quick answer

• Use a Chemex brewer and its specific bonded filters.
• Grind your coffee beans medium-coarse, like sea salt.
• Heat your water to 195-205°F (90-96°C).
• Aim for a coffee-to-water ratio of about 1:15 to 1:17 (e.g., 30g coffee to 450-510g water).
• Bloom the coffee grounds for 30-45 seconds.
• Pour water slowly in concentric circles.
• Let the brew finish, then remove the filter.
• Enjoy your clean, bright cup.

Who this is for

• Coffee lovers who appreciate a clean, nuanced cup.
• Anyone looking to elevate their home brewing game.
• People who enjoy the ritual of making coffee by hand.

What to check first

Brewer type and filter type

You’re here for the Chemex, so that’s set. The big thing with Chemex is its proprietary filters. They’re thick and bonded. Don’t even think about using a standard cone filter or a metal mesh one. It won’t work right and will mess up your brew. Make sure you’ve got the right Chemex filters for your brewer size.

Water quality and temperature

Good water makes good coffee. If your tap water tastes funky, your coffee will too. Consider filtered water. For temperature, you want it hot, but not boiling. Aim for 195°F to 205°F (90°C to 96°C). Too cool and you’ll get sour, underdeveloped coffee. Too hot and you risk burning the grounds, making it bitter. A gooseneck kettle is your best friend here for control.

Grind size and coffee freshness

This is critical for any brew method, but especially for pour-over like the Chemex. You want a medium-coarse grind. Think coarse sand or sea salt. Too fine, and water will struggle to pass through, leading to over-extraction and bitterness. Too coarse, and the water will rush through, resulting in weak, sour coffee. Freshly ground beans are key. Coffee loses its aromatic compounds fast after grinding. Grind right before you brew.

Coffee-to-water ratio

This is how much coffee you use for how much water. A good starting point for Chemex is a ratio between 1:15 and 1:17. That means for every gram of coffee, you use 15 to 17 grams of water. For example, if you use 30 grams of coffee, you’d use 450 to 510 grams (or milliliters) of water. Play around with this to find what you like best. It’s a simple adjustment that makes a big difference.

Cleanliness/descale status

A dirty brewer is a bitter brewer. Chemex is glass, so it’s easy to see. Rinse it out thoroughly after every use. If you have hard water, mineral buildup can happen over time. Descaling is important. A simple vinegar solution or a specialized descaling product can work wonders. Check your brewer’s manual for specific instructions, but generally, a clean brewer is a happy brewer.

Step-by-step (how to make coffee in a chemex)

1. Heat your water.

• What to do: Heat your filtered water to between 195°F and 205°F (90°C to 96°C).
• What “good” looks like: Water is steaming but not furiously boiling. A thermometer helps here.
• Common mistake: Using boiling water or water that’s too cool. Avoid this by letting boiling water sit for 30-60 seconds or using a temperature-controlled kettle.

2. Prepare the Chemex filter.

• What to do: Fold the Chemex filter into a cone shape. Place it in the top of the Chemex brewer, ensuring the three-layer side is against the spout.
• What “good” looks like: The filter sits snugly in the brewer, creating a good seal.
• Common mistake: Not unfolding the filter correctly, or not placing the thick side towards the spout. This can cause channeling or grounds to escape.

3. Rinse the filter.

• What to do: Pour hot water over the filter, wetting it thoroughly. Discard this rinse water from the Chemex.
• What “good” looks like: The filter is fully saturated, and the rinse water is gone. This removes paper taste and preheats the brewer.
• Common mistake: Forgetting to rinse the filter or not discarding the rinse water. This leaves a papery taste in your coffee.

4. Add your coffee grounds.

• What to do: Add your freshly ground, medium-coarse coffee to the rinsed filter. Give the Chemex a gentle shake to level the grounds.
• What “good” looks like: A flat bed of coffee grounds.
• Common mistake: Not leveling the grounds. This can lead to uneven extraction.

5. Bloom the coffee.

• What to do: Start your timer. Pour just enough hot water (about twice the weight of your coffee) over the grounds to saturate them evenly. Wait 30-45 seconds.
• What “good” looks like: The grounds puff up and release bubbles (this is CO2 escaping). It should look like a spongy, expanding mass.
• Common mistake: Skipping the bloom or pouring too much water. This is crucial for releasing trapped gases that can otherwise make your coffee taste sour.

6. Begin the main pour.

• What to do: After the bloom, start pouring the rest of your water slowly and steadily in concentric circles, starting from the center and working your way out, then back in. Avoid pouring directly onto the filter paper.
• What “good” looks like: A controlled, even pour that keeps the water level consistent and the grounds saturated.
• Common mistake: Pouring too fast, too aggressively, or all in one spot. This can create channels and uneven extraction.

7. Continue pouring in stages.

• What to do: Pause pouring periodically to let the water level drop slightly, but not so much that the grounds become exposed. Aim to complete your pour within 2.5 to 3.5 minutes.
• What “good” looks like: The water level is managed, and the brewing process looks controlled.
• Common mistake: Pouring all the water at once or letting the grounds dry out between pours. This leads to inconsistent extraction.

8. Let it drip.

• What to do: Once all your water is poured, let the remaining water drip through the coffee bed.
• What “good” looks like: The coffee bed is mostly drained, and the last drips are coming through.
• Common mistake: Removing the filter too early or letting it sit too long after it’s drained.

9. Remove the filter and serve.

• What to do: Carefully lift the filter with the spent grounds and discard it. Swirl the brewed coffee in the Chemex to aerate it.
• What “good” looks like: A clean, aromatic brew ready to be served.
• Common mistake: Letting the filter sit in the brewed coffee, which can lead to over-extraction and a bitter taste.

Common mistakes (and what happens if you ignore them)

Mistake	What it causes	Fix
Using pre-ground coffee	Stale flavor, lack of aroma, inconsistent grind	Grind beans fresh just before brewing.
Wrong grind size (too fine)	Slow drip, over-extraction, bitter taste	Coarsen your grind. Aim for medium-coarse, like sea salt.
Wrong grind size (too coarse)	Fast drip, under-extraction, weak, sour taste	Fine your grind. Aim for medium-coarse, like sea salt.
Water too hot (>205°F / 96°C)	Burnt coffee, bitter, harsh flavor	Let boiling water cool for 30-60 seconds, or use a temperature-controlled kettle.
Water too cool (<195°F / 90°C)	Sour, underdeveloped, weak flavor	Heat water to the correct temperature range.
Skipping the bloom	Trapped CO2, sour taste, uneven extraction	Always bloom for 30-45 seconds.
Aggressive or uneven pouring	Channeling, uneven extraction, bitter or sour	Pour slowly and steadily in concentric circles.
Pouring water directly on the filter paper	Washes away coffee fines, can affect taste	Pour into the coffee bed, not the filter itself.
Draining the filter completely dry	Can lead to over-extraction as water drips	Remove filter once dripping slows significantly.
Not rinsing the Chemex filter	Papery taste in the coffee	Always rinse the filter with hot water before adding grounds.
Using tap water with off-flavors	Unpleasant taste transferred to the coffee	Use filtered or good-tasting bottled water.
Dirty brewer or filter basket	Stale, rancid, or metallic flavors	Clean your Chemex thoroughly after each use.

Decision rules (simple if/then)

• If your coffee tastes sour, then try a finer grind because a finer grind increases extraction.
• If your coffee tastes bitter, then try a coarser grind because a coarser grind decreases extraction.
• If your coffee tastes weak, then try a higher coffee-to-water ratio (more coffee) because you’re using too much water for the amount of coffee.
• If your coffee tastes too strong, then try a lower coffee-to-water ratio (less coffee) because you’re using too little water for the amount of coffee.
• If your bloom is weak or non-existent, then check your coffee freshness because stale coffee won’t degas properly.
• If your brew time is too fast (<2 minutes), then try a finer grind because your current grind is too coarse.
• If your brew time is too slow (>4 minutes), then try a coarser grind because your current grind is too fine.
• If your coffee tastes papery, then you likely didn’t rinse the filter enough because paper filters can impart flavor if not properly pre-rinsed.
• If your water temperature is too low, then your coffee will likely taste sour and underdeveloped because extraction requires sufficient heat.
• If your water temperature is too high, then your coffee will likely taste burnt and bitter because excessive heat can scorch the grounds.

FAQ

What kind of coffee beans should I use with a Chemex?

You can use any whole bean coffee you enjoy. The Chemex highlights the nuanced flavors of single-origin beans, but it’s also great for blends. The key is to use freshly roasted, good-quality beans.

How much coffee do I need for my Chemex?

For a standard 8-cup Chemex, a good starting point is around 40-50 grams of coffee for about 600-750 grams of water. Always adjust to your taste preference and the specific brewer size.

Can I reuse a Chemex filter?

No, Chemex filters are single-use. They are designed to be discarded after brewing to ensure a clean taste and proper filtration.

Why does my coffee taste weak and sour?

This usually means your coffee is under-extracted. Check your grind size (it might be too coarse), water temperature (it might be too low), or coffee-to-water ratio (you might be using too little coffee).

Why does my coffee taste bitter and burnt?

This is typically over-extraction. Your grind might be too fine, your water too hot, or your brew time too long. Try adjusting these factors.

How long should the brewing process take?

The total brew time, including the bloom, should ideally be between 3.5 to 4.5 minutes for most Chemex sizes. This can vary slightly based on grind size and pour technique.

Is a gooseneck kettle necessary for a Chemex?

While not strictly mandatory, a gooseneck kettle is highly recommended. Its precise spout allows for controlled pouring, which is essential for even extraction in pour-over methods like the Chemex.

How do I clean my Chemex?

Rinse it thoroughly with hot water after each use. For deeper cleaning or to remove mineral buildup, use a mild dish soap and a soft brush, or a descaling solution. Always rinse thoroughly afterward.

What this page does NOT cover (and where to go next)

• Specific coffee bean sourcing and roasting profiles. (Explore coffee roaster websites or local shops).
• Advanced pour-over techniques like pulse pouring variations. (Look for advanced brewing guides).
• Detailed analysis of water chemistry for brewing. (Search for resources on water for coffee).
• Comparison of different Chemex filter types and their impact. (Check Chemex official resources or brewing forums).
• Troubleshooting specific machine malfunctions if you’re using an electric pour-over device. (Consult the device’s manual).