We’ve already written why filtered coffee is the healthiest type of coffee (yes, really). Now, science is back with another piece of coffee knowledge: how to make a tastier cup of pour-over coffee.
At the heart of this new insight lies a deceptively simple trick — change how you pour. More specifically, how high you pour from. A team of scientists from the University of Pennsylvania has shown that by carefully manipulating the height and flow of water in pour-over coffee, drinkers can coax out a stronger, richer brew — even while using fewer beans.
“What we recommend is making the pour height as high as possible, while still maintaining a laminar flow, where the jet doesn’t break up when it impacts the coffee grinds,” said author Ernest Park.
The science of a perfect pour
A couple billion cups of coffee are consumed every day. From moka pots to espressos and filter coffee, there’s no shortage of ways to make a morning brew. Each method has its loyalists and rituals — including a specific grind size, water temperature, bloom time, brew ratio. And yet, for all the obsessive tinkering that surrounds coffee culture, most of us are guided more by habit than by hard science.
Even among aficionados, brewing is often more art than experiment. But a team of researchers at the University of Pennsylvania believes we can do better. They wanted to find out if adjusting just one variable — how high you pour from — could significantly change what ends up in your cup.
The study began with an unusual challenge: how to look inside a cup of coffee without being blinded by its darkness. So the researchers swapped out the opaque coffee grounds for transparent silica gel particles. These were placed inside a glass funnel, lit by a laser sheet, and recorded with a high-speed camera.
The visuals revealed something unexpected. When hot water was poured from a sufficient height — and in a steady, unbroken stream — it bored into the bed of particles, setting off a kind of mini landslide. Particles on the sides collapsed and tumbled down into the center, in what the researchers dubbed an “avalanche” effect. More mixing means more contact between the water and the grounds. And more contact means more flavor is extracted.
A simple way to achieve the right flow
The researchers note that, in particular, pouring the hot water slowly from a goose-neck kettle achieves the ideal height and flow. This creates a slow but focused water jet that favors a tasty brew. It displaces grounds and recirculates deeper into the coffee bed, allowing for better mixing the water and grounds.
Gooseneck kettles are already favored by many pour-over fans. But if you don’t have one, try to emulate the type of flow created by a gooseneck kettle. Just make sure that the stream doesn’t break up into droplets.
Researchers found that with this type of flow, you can get a tasty brew even with less coffee. The team recommends experimenting at home. Start by using 10% fewer coffee grounds — say, 18 grams instead of the usual 20. Then pour hot water slowly and steadily from about 30 centimeters above the grounds. That’s about a foot — a manageable and safe height. And always aim to keep the stream intact.
While the researchers don’t plan to continue studying coffee specifically, they say this kind of kitchen-based physics can open new scientific doors.
“We can really learn something from both the chemistry and physics point of view by looking at the kitchen,” said author Arnold Mathijssen. “It leads to new science where you didn’t expect it.”
Journal Reference: Pour-over coffee: Mixing by a water jet impinging on a granular bed with avalanche dynamics, Physics of Fluids (2025). DOI: 10.1063/5.0257924
