For the longest time, the coffee community only cared about water’s impact ruining espresso machine boilers and kettles. But what about water’s impact on coffee flavour?

In this episode, I tell the story of how the specialty coffee community came to understand water chemistry: the pioneering work of the computational chemist Christopher Hendon and British roaster Maxwell Colonna-Dashwood, the genesis of the SCA’s Water Quality Handbook, and where we are today understanding the impact of minerals on our water.

I strongly recommend listening to the two episodes before this one first Getting great water for coffee, step-by-step & The two ingredients in water that ruin your coffee, and the ancient story behind them

Please spread the word about The Science of Coffee!

Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter

Want to go deeper into water chemistry?

Read the SCA’s Water Quality Handbook

Season 3 of The Science of Coffee is made possible by these leading coffee organisations:

The Coffee Quest | BWT | TODDY | Algrano | Probat

Note: this is a reworked version of my 2022 episode Water for Brewing Coffee, including portions of my 2024 episode How to think like a scientist, part 2.

550 million years ago, earth was perfect. We had perfect water for coffee AND we were living in a vegetarian paradise!

But then Earth changed—violently. The planet shifted from a peaceful, plant-eating paradise to a darker, more brutal world. And in this new world, the chemistry of water was forever altered.

This is the wild story of how earth-shaking forces and the spirits of long-dead critters ruin your coffees today.

This story will help you remember the two invisible ingredients in your water that have a huge impact on coffee flavour and your brewing equipment: calcium and hydrogen carbonate.

Read Marcia Bjonerud’s amazing book, Reading the Rocks

Please spread the word about The Science of Coffee!

Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter

Season 3 of The Science of Coffee is made possible by these leading coffee organisations:

The Coffee Quest | BWT | TODDY | Algrano | Probat

Note: this is a reworked version of my 2022 episode Water for Brewing Coffee.

Water massively impacts your coffee’s flavours. But most of us struggle to fix our water because water science is confusing…

…until now! In this special collaboration with Lucia Solis (Making Coffee podcast), I guide her through the two most important concepts you need to understand to get great-tasting water for coffee: hardness and alkalinity.

We go step-by-step through:

• Why these concepts matter for coffee flavour and equipment

• How to test your water at home

• How to fix it, depending on what you’re working with

These aren’t one of my usual narrative episodes—they’re a straightforward, practical guide to help you take control of your water.

By the end of these episodes, you’ll be able to say: “I know what good water for coffee is and how to get it”.

I hope it helps you as much as it helped Lucia.

Check my website for all the visuals mentioned in this episode, including: 

SCA graph for excellent water (the “map”)

Map of different water hardness across Paris

My Berlin water report

The nightmarish table of conversions…

Results from my water tests in my Berlin studio

Bottled water brands rated for their hardness and alkalinity

Please spread the word about The Science of Coffee!

Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter

Resources mentioned in the episode: 

SCA’s Water Quality Handbook

Hardness and alkalinity dripper testing kit (also good for keeping your fishies happy)

BWT Penguin Filter Jug (what I used to use with the magnesium cartridges)

BWT BestAqua ROC (what now I use)

BWT BestBarista (for cafes)

Create your own water by adding minerals to very soft or distilled water: JoJo Hersh’s simple calculator using epsom salts and bicarbonate of soda, and Barista Hustle’s more elaborate one. 

Want to go deeper into water chemistry?

Read The Craft and Science of Coffee

Season 3 of The Science of Coffee is made possible by these leading coffee organisations:

The Coffee Quest | BWT | TODDY | Algrano | Probat

Water massively impacts your coffee’s flavours. But most of us struggle to fix our water because water science is confusing…

…until now! In this special collaboration with Lucia Solis (Making Coffee podcast), I guide her through the two most important concepts you need to understand to get great-tasting water for coffee: hardness and alkalinity.

We go step-by-step through:

• Why these concepts matter for coffee flavour and equipment

• How to test your water at home

• How to fix it, depending on what you’re working with

These aren’t one of my usual narrative episodes—they’re a straightforward, practical guide to help you take control of your water.

By the end of these episodes, you’ll be able to say: “I know what good water for coffee is and how to get it”.

I hope it helps you as much as it helped Lucia.

Check my website for all the visuals mentioned in this episode, including: 

SCA graph for excellent water (the “map”)

Map of different water hardness across Paris

My Berlin water report

The nightmarish table of conversions…

Results from my water tests in my Berlin studio

Bottled water brands rated for their hardness and alkalinity

Please spread the word about The Science of Coffee!

Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter

Resources mentioned in the episode: 

SCA’s Water Quality Handbook

Hardness and alkalinity dripper testing kit (also good for keeping your fishies happy)

BWT Penguin Filter Jug (what I used to use with the magnesium cartridges)

BWT BestAqua ROC (what now I use)

BWT BestBarista (for cafes)

Create your own water by adding minerals to very soft or distilled water: JoJo Hersh’s simple calculator using epsom salts and bicarbonate of soda, and Barista Hustle’s more elaborate one. 

Want to go deeper into water chemistry?

Read The Craft and Science of Coffee

Season 3 of The Science of Coffee is made possible by these leading coffee organisations:

The Coffee Quest | BWT | TODDY | Algrano | Probat

Every time we open a bag of beautiful specialty coffee — like Erick Bravo’s from Finca El Chaferote in Huila, Colombia — we’re drinking something that’s been on a long journey.

And I mean long! Over 1500 kilometers north up and down the Andes mountain range, a distance more than twice the height of France.

Along the way, it passes through dozens of hands, machines, and decisions. We follow it through muddy mountain sides, dusty dry mills, and hurricane-battered coastal warehouses — places where all kinds of things can go wrong. A leaky roof. An overly aggressive polishing machine. Or even theft.

But here’s the mystery: getting Erick’s coffee to port costs 50% more than sending a commodity coffee through the same route.

Why?

That question led me deep into Colombia’s coffee supply chains — and what I found changed how I think about the real cost of treating coffee with care.

Please spread the word about The Science of Coffee!

Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter

Find your next favourite Colombian coffee from The Coffee Quest

Taste coffees from Erick Bravo’s award winning farm, Finca El Chaferote, and follow him on Instagram. 

Season 3 of The Science of Coffee is made possible by these leading coffee organizations:

The Coffee Quest | BWT | TODDY | Algrano | Probat

I travel to Colombia’s Huila region to answer a question that’s puzzled me for years: if specialty coffee pays more, is better for the environment, and brews tastier cups—why don’t more farmers grow it?

I speak with two producers in the same region whose choices couldn’t be more different. One stakes his future on specialty. The other opts out.

Their decisions come down to more than passion or a hard work ethic. Instead, I uncover two  starting conditions—often invisible to us buyers—that strongly shape whether a farmer chooses specialty at all.

If we want to see more speciality coffee grown, we need to bring down the barriers to specialty. But first we need to understand what those barriers really are.

The answers might surprise you. They surprised me.

Please spread the word about The Science of Coffee!

Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter

Find your next favourite Colombian coffee from The Coffee Quest

Taste coffees from Erick Bravo’s award winning farm, Finca El Chaferote

Nerd out on my farm profitability estimations

Season 3 of The Science of Coffee is made possible by these leading coffee organizations:

The Coffee Quest | BWT | TODDY | Algrano | Probat

Volume. Cheap. Lame flavours. This is the traditional way of growing coffee in Brazil, and almost every farm does it this way. 

But what if you wanted to produce beautiful, distinctive flavours instead—and make a living from it?

In this episode, we travel to Fazenda Paraíso in Minas Gerais, Brazil, where farmer Vicente Pereira and his daughter are on a steep learning curve finding buyers for their beautiful coffees. 

Part 2 explores what it looks like for a small Brazilian farm to find better buyers, and the challenge of achieving pricing power. 

Behind every beautiful coffee is a family story like this, but it’s a story we rarely get to see close up. 

Let’s take a closer look.

Please spread the word about The Science of Coffee!

Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter

Source your next lot of specialty green coffee on Algrano

Listen to Firefly to hear a cautionary tale about a specialty farm failing because they couldn't find the right buyers.

Try Fazenda Paraiso's and Sancoffee's coffees for yourself!

Season 3 of The Science of Coffee is made possible by these leading coffee organizations:

The Coffee Quest | BWT | TODDY | Algrano | Probat

Volume. Cheap. Lame flavours. This is the traditional way of growing coffee in Brazil, and almost every farm does it this way. 

But what if you wanted to produce beautiful, distinctive flavours instead—and make a living from it?

In this episode, we travel to Fazenda Paraíso in Minas Gerais, Brazil, where farmer Vicente Pereira and his daughter are on a steep learning curve finding buyers for their beautiful coffees. 

Part 1 unravels the hidden structures of Brazil’s coffee industry: how prices are set, why it’s so hard to create a specialty-focused farm, and why Vicente's farm is unsustainable if he sells his coffee the traditional way. 

Behind every beautiful coffee is a family story like this, but it’s a story we rarely get to see close up. 

Let’s take a closer look.

Please spread the word about The Science of Coffee!

Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter

Source your next lot of specialty green coffee on Algrano

Listen to Firefly to hear a cautionary tale about a specialty farm failing because they couldn't find the right buyers.

Try Fazenda Paraiso's and Sancoffee's coffees for yourself!

Season 3 of The Science of Coffee is made possible by these leading coffee organizations:

The Coffee Quest | BWT | TODDY | Algrano | Probat

To roast coffee faster, you need to turn up the heat….right?

No! 

In this episode, we explore the three powerful methods of heat transfer that revolutionised roasting. We’ll journey from humble beginnings—when roasting three kilos took half an hour—to machines that now roast hundreds of kilos of coffee in the time it takes you to boil a kettle. 

But beans roasted at lightning speed look strange, and taste… well, you’ll find out. Join us as we test-drive an industrial tangential roaster where first crack remind me of fireworks crackers. 

We also see the whale-sized roaster so massive it’s worth you a Guinness World Record. 

We have the technology today to roast coffee faster than ever, so why aren’t we all roasting at recording-breaking speeds?

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Check out the Probat roasters mentioned in this episode:

Emmerich Spherical Roaster - "Pink Hydrant"

Large ball roaster - “Sputnik in a pizza oven”

G45 early drum roaster - “Old school steam train” 

Early tangential roaster

Sample tangential roaster - "Shoebox"

Neptune 4000, the largest drum roaster in the world! - "The whale"

And there are lots of other specialty roasters from Probat I didn't have time to showcase, including their new hydrogen powered roasters. See them all for yourself!.

Theodor von Gimborn's wikipedia page

Go deeper into the science of roasting

Read Mark Al-Shemmeri’s coffee roasting blog

Do a Certificate of Advanced Studies with the Coffee Excellence Centre

Explore Barista Hustle's online roasting learning

Learn more from Morten Münchow and his coffee roasting courses

Read Morten’s paper in collaboration with the University of Copenhagen on Roasting Conditions and Coffee Flavour

Follow Filter Stories on Instagram for my infographics

Learn more about first crack on my episode Coffee Roasting, Part 1: How heat transforms coffee beans

Season 3 is made possible by these leading coffee organizations:

The Coffee Quest | BWT | TODDY | Algrano | Probat

A mother coffee plant gifts its baby everything it needs to grow—a green seed packed with food. But when we roast coffee, we hijack that gift and turn it into something else: flavor.

But what is flavor, at a microscopic level? What actually happens inside the bean when heat meets those nutrients?

In this episode, we shrink down to witness the Maillard reaction up close—a wild chain of molecular collisions that transforms baby plant food into aromas we adore. 

Grab your popcorn - you’re getting a front row seat at the wildest chemistry show in coffee. 

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Please spread the word about The Science of Coffee!

Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter

Ethiopian forest sounds curtesy of George Vlad. Hear more nature sounds here.

Go deeper into the science of roasting

Do a Certificate of Advanced Studies with the Coffee Excellence Centre

Grab a copy of Anja Rahn's upcoming book on coffee science through her Instagram

Explore Barista Hustle's online roasting learning

Learn more from Morten Münchow and his coffee roasting courses

Read Morten’s paper in collaboration with the University of Copenhagen on Roasting Conditions and Coffee Flavour

Follow Sebastian Opitz on LinkedIn

Follow Filter Stories on Instagram for my infographics

Season 3 is made possible by these leading coffee organizations:

The Coffee Quest | BWT | TODDY | Algrano | Probat