Coffee Science: How to Make the Best Pourover Coffee at Home

Brewing coffee is a balancing act. Between different roasting styles, brewing techniques, and new coffee gear, it can be tricky to know what brew method is right for you. It's helpful, then, to back up and understand how coffee brewing works and how brew methods differ. Then, you can make an informed decision about which devices and methods might work best for the type of coffee you like to drink.

Here, we’ll focus on the physical and chemical processes that make up coffee brewing, starting with one of the most simple (and increasingly popular) methods: the pourover. We’ll also provide a step-by-step guide to pourover brewing, as well as gear recommendations.

Why Pourover Brewing is Different

Pourover coffee (unlike immersion brew methods, like a French press) continuously saturates the coffee grounds with fresh water for the majority of the brewing cycle. This promotes a faster, more efficient brew. On the other hand, fresh water also has a tendency to extract more from the surface layers of the grounds. So, when brewing pourover coffee promoting even extraction is key. We’ll go over how to do this below. Pouring one stream of water (rather than the showerhead of an automatic drip coffee maker) also means that the water can travel through the grounds unevenly, extracting more from one part of the coffee bed than another.

This is all to say that manual brew methods, like pourover, put more brew variables directly in the hands of the person making the coffee. That leaves room for experienced brewers to manipulate the flavors in their cups, but it also means that pourover novices might find that they’re not getting the results they hoped for right away. 

However, understanding how coffee brewing works can demystify pourovers. Let’s go over the three main extraction phases that occur during all coffee brewing: wetting, dissolution, and diffusion.

Phases of the Extraction Process

Wetting

Wetting is just what it sounds like: the coffee is dry and you make it wet. The reason you need to think about it as an entire phase is because it's not as simple as it sounds. One of the major byproducts of roasting coffee is carbon dioxide gas. For lighter roasted coffees, that carbon dioxide is trapped in the cell structure of the coffee bean, and leaches out slowly over weeks. With dark roasted coffees, the roasting process has physically blown a hole in every cell, and most of the CO2 is out within just a few days. This attribute of dark roasts (coffee roasted past the "second crack" phase) is also why there are some notes below about how roast level can affect brewing.

When you hit the coffee grounds with hot water, CO2 is able to escape and it bubbles out. The problem is that if carbon dioxide gas is going out, water isn't able to get in. Picture shoppers on Black Friday. If you opened the store for business at the same moment there was a panicky fire drill, you could have a mess on your hands. That is unless everyone wanting in waited until everyone wanting out got out.

As you start your pourover brew, you'll want to add just enough brewing water to wet all of the grounds, then stop and let the gas escape for about 30 seconds. You'll see the bed of grounds swell and expand, resulting in what coffee professionals call a "bloom." This step also helps the coffee grounds fully saturate, and extract solubles from the center of each grind particle and not just the edges.

Dissolution

The word "dissolution" looks a lot like the word "dissolve," and that's just what it's about. Once the coffee grinds are fully wetted, the hot water will dissolve the solubles (also called solutes) in the beans' cells.

Part of what makes great coffee brewing difficult is that the complex cocktail of organic substances in coffee includes both pleasant and unpalatable types. Lucky for us, it's one of the convenient facts of coffee chemistry that the desirable and tasty solubles dissolve in water more readily than the unpleasant-tasting substances, so getting a tasty brew is all about stopping the brewing at the perfect moment—after you've dissolved the good flavors but before those nasty flavors start to dominate.

Diffusion

Diffusion takes that dissolved stuff and transports it out of the coffee grounds via a term you might not have heard since school: osmosis. The cell wall structures of our coffee grounds are semi-permeable membranes, so the osmosis pressure drives the brew out of the highly concentrated chambers of the coffee grounds out to the more watery surrounding environment.

In an immersion brew, like a French press, this process happens naturally while the coffee is fully saturated and sitting inside the brew water. Diffusion in pourover brewing occurs as new water is added to the filter and helps rinse the brewed coffee full of dissolved coffee solids into the vessel below. 

The Variables: How You Can Tweak Extraction

Most of the roasted coffee bean, about two-thirds of the bean's mass, is insoluble cellulose, which is basically the same stuff that makes up tree bark or the stem of a dandelion. The other third is dissolvable in water. Of that soluble third, most of it is good stuff (particularly various organic acids and sugars). The rest is longer-chain molecules that we associate with astringent and bitter tastes. Where we find the happy flavor balance is at the 19-22% extraction point (that is, extracting 19-22% of the coffee's mass). More than that and you'll find those astringent and bitter flavors start to dominate. Less than that and the resulting flavors will be thin and unbalanced—and with lighter roasted coffees, unusually sour.

Ultimately, there are five main variables in coffee brewing that you control that will influence extraction: the ratio of coffee to water, grind size, brew time, brew temperature, and agitation. High-quality automatic drip brewers will marry a consistent, ideal brewing temperature (around 198-202ºF) and time with an evenly dispersed showerhead. As long as you put the right amount of water in the reservoir, weigh out the proper ratio of coffee, and grind it at the right setting, you’ll have a repeatably delicious brew.

However, as we've noted before, pourover puts all of these brewing variables in the hands of the brewer. The ratio of coffee to water can change, grind size and uniformity depend a lot on the quality of the grinder you're using, the brew time varies in relation to the speed of the pour, temperatures can fluctuate, and agitation can be uneven depending on how forceful the pour is. 

All of those variables can affect the speed and evenness at which the flavor solubles in coffee can be extracted. With that in mind, investing in some equipment is helpful.

Pourover Gear: What Equipment Do You Need?

• Digital scale (that can read in grams—might we also suggest a coffee scale?)
• Gooseneck kettle
• Burr grinder
• Timer
• Pour-over device of choice and filter (we like the Kalita Wave 185 Dripper)
• Filtered water
• Coffee

Put it All Together: How to Brew Pourover Coffee

Below you’ll find a step-by-step guide for pourover brewing at home with added footnotes to help detail the why of each step. It’s also important to note: everybody’s setup at home is unique! No two coffee grinders grind exactly the same way, and even different levels of mineral content in water will affect extraction. You should use this guide as a starting point and adjust to find a specific recipe that works for you.

1. Heat your water.
2. Weigh your coffee.
3. Choose the right grind.
4. Rinse your filter.
5. Add your coffee to the filter.
6. Start your bloom.
7. Time your pour
8. Let it drip.

Fill your kettle and start heating.

Some electric kettles (like our favorite gooseneck model from Fellow) have temperature controls—if so, try setting it to between 205-210ºF and see what temperatures work best for you. Hotter temperatures might accentuate harsh smoky flavors in a dark roast, but cooler temps might not pull out the sweetest flavors in a light roast. Finding the best starting temperature depends on the coffee you enjoy drinking, and how it impacts the flavors you’re looking for. It is helpful to note that anytime you pour water from one vessel into another, you lose about 10 degrees. So, if we’re aiming for 200ºF as an ideal brew temperature, that means setting your kettle to a near-boil (210ºF) and beginning to pour after the rolling bubbles have settled (about 30 seconds).

Note: Water quality can have a dramatic effect on your coffee. For instance, water that’s too soft has a hard time actually pulling the good-tasting solids out of the coffee bed. At the same time, it’s really hard to control the chemical makeup of your tap. A good rule of thumb is to start with a carbon water filter, like the kind that nestles into a pitcher that you keep in your fridge. And if you want to go down the rabbit hole there are entire books dedicated to custom water mineral blends for coffee brewing. 

Weigh out your coffee.

When choosing how much water and coffee to use, there are a number of things to consider. If you don’t use enough coffee, there won’t be a deep enough bed depth to slow down the flow of water and your brew will be thin and weak tasting. If there’s too much coffee, you run the risk of overflowing the brewer. A good starting point for most pourover brewers is 30 grams of coffee and 500 grams of water. We suggest a coffee-to-water ratio between 55-65 grams of coffee per liter of water (a mass ratio between 1:16 and 1:14.)

When brewing, the most accurate way to maintain a consistent ratio is by placing your whole brewing rig on a digital scale. That way you can measure exactly how much water is being added to your coffee. A few grams of water won’t make a huge difference in the cup, but in darts, it’s easier to score big if you’re aiming for the center of the bullseye. 

Grind your coffee.

The size of your coffee grind has perhaps the biggest impact on coffee flavor and strength. A grind that’s too coarse won’t allow the water to extract the flavor solids from inside the bigger particles, and your brew will taste weak and lightly sour. Too fine, and you’ll get a brew that’s astringent, bitter, and strong. The finer the grind is, the more surface area you’ve exposed for the brewing water to extract. A well-calibrated burr grinder is necessary to not only have a wide variety of grind size options but also to have a precise, even particle size to promote even extraction. 

This makes grind the perfect variable to focus on when trying to adjust for flavor. If you can set your other brewing variables into a consistent pattern, adjusting the grind slightly coarser or finer will tweak the flavor of your coffee. Start with something in the medium range of the grinder, which should look like raw sugar crystals, and go from there. 

Set up your brew rig with a filter rinse.

By setting your filter into your dripper and rinsing it with hot water before adding any coffee, you can achieve a few things:

1. Help rinse away any papery flavor that might get pulled into the brew.
2. Help the filter seat properly so it holds its shape when you start the pour.
3. Pre-heat the dripper and the brew vessel to help regulate both brewing and serving temperatures.

You should use enough water to thoroughly wet the filter, and be sure to discard any rinse water before brewing. 

Add coffee, prepare to pour.

This is a great chance to place your dripper and brew vessel on a scale and zero it before adding the ground coffee, double-checking that your coffee weight is correct. There’s only so much room for the particular type of heartbreak that occurs when you take your first sip and realize oh shoot, some of the coffee is still in the grinder, or wait, I was a little sleepy, how much coffee did I actually weigh out?

Bloom it. Time it.

We are now kicking off the brew process. Add around twice as much water as there is coffee (60g of water for 30g of coffee) to wet the grounds, trigger the release of CO2, and start your timer. When we time a coffee brew, we are doing so from the moment hot water touches the grounds to when it stops dripping. 

Measuring the total brew time helps establish a baseline. It’s difficult to extract everything you want to out of a pourover brew in less than two-and-a-half minutes. At the same time, if the brew is dragging on past five minutes, it’s likely to start pulling in those astringent flavors. Most pourover brewing has a sweet spot right around three to four minutes, and if you establish a consistent brew time, you can then rely on grind size as your main variable. 

When you add that first amount of water, you should notice the coffee starts to expand as it releases CO2 gas. We’re in the coffee-wetting phase, and you should establish a preferred time to let the coffee bloom. Anywhere between 30-60 seconds is a good starting point, but once you pick a time it’s best to stick with it to keep your overall brew times consistent. 

Continue to brew.

Anytime agitation is added into a coffee brewing process, solubles tend to extract faster. Think about stirring sugar into lemonade—the more you stir, the faster it dissolves. The pour can create different levels of agitation in your brew bed, and can even cause the water to channel through one section of the coffee more forcefully and extract from that area unevenly. If your brew is extracting more from the center than the outside edge of the coffee bed, you might find that your cup tastes both astringent and bitter and sour, while lacking balanced sweetness. This is because the center has extracted more of the solubles available while the outside ring has only dissolved the more sour-tasting organic acids. Making sure the coffee bed is evenly saturated during the brew process helps ensure sweetness, balance, and clarity of flavor.

When you begin your pour start with a water stream about as thick as a pencil and work in consistent concentric circles from the center outwards and back towards the middle. The goal is to saturate all the coffee evenly and to get the coffee grounds to settle into a flat bed.

The distance that your brew water drops can affect brew temperatures, as well as increase or decrease the amount of agitation the falling water creates wherever it falls in the coffee bed. In general, the lower you pour from, the better, if for no other reason than it's easier to maintain consistency.

Try adding water in pulses—pour around 100 grams for about 10 seconds, then let it start to drain for about 10-15 seconds. Before the coffee bed is fully exposed, add another pulse of water in the same pattern until you reach your total target water weight. (Again, a good starting point is 500 grams of water for 30 grams of coffee.) The goal is to have a consistent column of brew water covering the bed of coffee and to replenish it before the grounds are exposed to air. 

Let it drip.

When you stop adding water, your dripper will continue to drip between 20 and 60 seconds. This should be counted as part of your total brew time. If you hit your target (say, three-and-half minutes), then you know you’ve maintained a consistent brewing process and any adjustments can be made one at a time. 

Sip, and ponder.

The ultimate coffee test is whether or not the final brew is tasty. Is it too strong? Too weak? Too bitter? Too sour? Or is it just that perfect blend of strength and sweetness, with the specific flavor characteristics of the coffee you chose shining through? Nailing the timing and pouring can take practice, but once your routine is set, it’s easy to brew coffee at home that tastes like it does at your favorite cafe. 

However, if you're not happy with your final cup, consider the coffee itself and its roast level. A darker roast will always exhibit smoky, bitter flavors that a medium roast or lighter roast won’t. A light roast will tend to showcase more of the coffee’s fruit acids and be brighter and more tart. Adjusting brew variables can make small adjustments to the flavor profiles of those coffees in the cup, but the predominant characteristics you will taste are forever tied to that roast level. Sometimes, you might just need to try a different coffee to find what you’re looking for.

FAQs

Do I need a burr grinder to brew good coffee?

Technically, no. But it’s really, really hard to do so without one. It’s even pretty hard to brew great-tasting coffee with a low-quality burr grinder. Coffee extraction relies on a precise cutting action in the grind to create good surface area combined with consistent grind particle size to promote evenness of extraction. Good quality burr grinders might seem expensive, but they tend to last a long time and many can be repaired almost infinitely. 

How important is a digital gram scale for coffee brewing?

Pretty important! Accuracy aside, scales help promote consistency. If you know exactly how much coffee you’re starting with and exactly how much water you’re using, you can then create a repeatable brewing process that will let you tweak it in subtle ways to achieve the cup you want. 

Should I buy a gooseneck kettle for pourover coffee brewing?

A gooseneck kettle has an elongated and curved spout, like the neck of a goose, which can help you control the flow rate and speed at which you pour water. A gooseneck kettle won’t immediately make your coffee taste better, but it will help promote control and consistency, which are two key concepts in repeatable, delicious coffee. 

What's the best pourover coffee maker?

We reviewed 15 pourover coffee makers and named the Kalita Wave Stainless 185 Dripper and Hario V60 Mugen Coffee Dripper our favorites. Both of them are great all-around brewers and can be paired with their corresponding carafes for full setups.

What should I do if my coffee tastes sour/bitter?

Coffee that tastes predominantly sour or bitter could mean that it wasn't brewed properly. Different flavors in the coffee extract at different rates, so sour coffee is a good indicator that your brew is under-extracted while excessive bitterness indicates over-extraction. The easiest fix is to change your grind: grinding finer will extract more and cut down on sourness while grinding coarser will extract less and eliminate bitterness.

Why We're the Experts

• Nick Cho is a coffee expert and barista champion. He's written numerous coffee-related stories for Serious Eats.
• Jesse Raub was the site's commerce writer and has more than 15 years of experience in the specialty coffee industry.
• We've separately reviewed various pieces of pourover gear, be it brewers, gooseneck kettles, or coffee scales.