The two ingredients in water that ruin your coffee, and the ancient story behind them

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! Leave a 5 star rating on Spotify Follow me on Instagram and tag me in an Instagram story Write a review on Apple Podcasts 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. How does Perfect Moose detect what kind of milk is in the pitcher? Click here to find out. See the Mikafi countertop roaster at the Thermoplan stand (6637) at World Of Coffee Brussels. Not attending? See it here . What does the Marco MilkPal look like to you? WALL-E? Something Steve Jobs would be proud of? Check it out here .

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The two ingredients in water that ruin your coffee, and the ancient story behind them is an episode from The Science of Coffee by James Harper.

This episode is 38:40 long.

This episode was published on Jul 28, 2025.

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