Water for Coffee
So you’ve made it far enough down the rabbit hole that you are considering altering your water for optimal brewing? For me, accepting the expensive grinder, scale, gooseneck kettle, and pour over dripper still weren’t enough to consistently make a brew as tasty as my local specialty shops was a big step. It seemed annoying and intimidating initially and easy to scoff at—if I was doing nine out ten things right why would this one parameter hold me back so much? While it’s frustrating, it can’t be ignored and the sooner it is fixed, the sooner you can enjoy fully the beans you are spending your hard-earned money on. I’ll first explain why it matters so much, delve slightly (very slightly) into the science, and give you additional resources and easy ways to make sure you have good water for brewing. If you’re totally uninterested in the details you can skip to the last paragraph where I will provide links for simple solutions to great water.
When it comes to brewing good coffee, you must have three things: Good coffee, a good grinder, and good water. If one is lacking, you will be missing out on loads of potential flavor. Truly, the importance of water on your coffees flavor cannot be overstated. And while coffee is a powerful flavoring agent, water still makes up roughly 98.5% of the contents in the cup of coffee you’re drinking every day. So then, it should be obvious that clean, good tasting water is a must and thus one of the most important parameters for good brewing water is being 100% free of chlorine. The taste of chlorine is obvious and can dominate/muddle the sweetness and subtle flavors in a cup of coffee. So perhaps a Brita filter you say? The Brita filter does help clean up the taste of some waters by filtering out chlorine so in some cases, depending on where you are starting with your particular tap water, Brita could work well but often it is insufficient or may even make the problem worse for reasons I will get back to shortly.
Unfortunately we can’t solely trust taste to guide us to the right water for brewing. Good tasting water might still, and often does, brew bad coffee. So now we get into a little chemistry.
All water, save distilled, isn’t just water. It has picked up other minerals along the way and/or have been intentionally treated with things like chlorine to make it safe. You can get a rough and easy measure by total dissolved solids (TDS) but this doesn’t tell you how much of each mineral there is which is important. This is because certain minerals like calcium and magnesium have very high binding energies which attach strongly to flavor compounds in coffee and bring them into the final cup whereas minerals like sodium (Na+, not table salt) affect extraction minimally. This is where a Brita filter can get you into trouble because while it gets rid of chlorine, it also softens the water by replacing calcium with sodium which might be ok if you are on the upper end of the acceptable level but if you are on the lower end, the Brita filter might then cause significant flavor loss. Another important factor is bicarbonate/alkalinity. Bicarb acts as a buffer, constantly trying to keep the pH where it was by altering some of the acidic compounds in coffee. It is important that calcium, magnesium, and bicarb be in balance. Too much calcium and magnesium and the coffee will be bitter and chalky. Too much bicarb and we won’t experience the bright acidity in the cup.
So, how much of each do you need? You can find the SCAA standards here but it is important to note there isn’t a perfect water recipe for coffee and many coffee professionals have their own recipes you can check out and try to mimic like Scott Rao and Matt Perger (Perger’s Barista Hustle is a fantastic resource to learn about all things coffee). To do this you’ll need a scale, distilled water, Epsom salts, baking soda, magnesium chloride hexahydrate, calcium chloride anhydrous, and potassium bicarbonate, all of which can be purchased on Amazon. If you go this route, as Jonathan Gagne points out in his blog, please buy food grade, not lab grade materials. Here you can find a list of detailed recipes different coffee professionals use and recommend. They all have many things in common and you could even make your own water, adding slightly more of one component and take notes on what works best for you. Magnesium tends to bind more strongly to fruity, acidic compounds while calcium binds to heavier, creamier compounds so you could alter ratios of those components and see what happens.
A final note before practical applications, this chemistry matters only when the water is actually involved in extraction of the coffee grounds. So, if you are adding water to espresso to make an Americano, adding water to a cold brew concentrate, or using ice in a Japanese iced coffee, the only parameter that matters is that the water is clean and tastes good.
Ok so you probably aren’t going to remember or care about most of the chemistry and an even smaller percent of you will want to put the effort into making your own water (it’s an admittedly extreme solution). But you probably do still want great coffee. So what do you do? Luckily two companies are making things easy on you: Third Wave Water and Peak Water. Third Wave are pre-prepared packets of minerals suitable for one gallon of distilled water you can purchase at the grocery store while Peak Water looks like a Brita pitcher ready to launch into space and comes with test strips for your tap which will then direct you how to adjust the pitcher to transform your tap water into great water for coffee. Both require a bit more investment than just tap water, but if you are spending the extra money on good coffee, it would be a waste not to brew it with good water.
- “The Best Water for Coffee.” James Hoffman Youtube channel.
- “Water for Coffee Extraction.” Ad Astra Coffee Blog by Jonathan Gagne.
- “Maxwell Colonna-Dashwood on the Complexities of Water and Flavor.” Video on Home-Barista.com. Link.
 If you live in and use the water of Fairmont, West Virginia—where our roastery is located—I suspect this is what happens to our water when we use a Brita filter. Our tap water is decent of brewing coffee with the main negative quality being the presence of chlorine. But I found my cups of coffee at home where significantly worse when using a Brita filter. What may have happened is the chlorine was gone and no longer obscuring the taste of my coffee, but the taste not being obscured was much worse because I couldn’t obtain a decent extraction after it softened (removed some of the calcium from) the water. I can’t currently prove this and your results may vary of course.