Getting great water for coffee, step-by-step. Part 1: Alkalinity, hardness and why it matters

The Science of 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

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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?

BWT White Paper on the effects of magnesium (German)
Christopher Hendon’s book Water for Coffee
Do an online Certificate of Advanced Studies at the Coffee Excellence Centre

Read The Craft and Science of Coffee
Barista Hustle's Water course
Some water content on YouTube by James Hoffman and Lance Hedrick

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

The Coffee Quest | BWT | TODDY | Algrano | Probat