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What You Need to Know about Water for Coffee: The Best Ratio, Temperature, and More

What You Need to Know about Water for Coffee: The Best Ratio, Temperature, and More

Words Erin Meister

While the beans are always the thing we obsess about when we talk about making really delicious coffee, there’s actually another ingredient involved that is—believe it or not—possibly even more important to your finished brew: Water!

Find out the perfect ratio of coffee grounds to water, the right temperature to brew it, and the best type of water to get your best-tasting cup of coffee ever.

That’s right, we need to pay good and close attention to this see-through stuff if we want to achieve the best we can every single morning (and noon, and occasionally night). 

There are four main areas of focus when we talk about water, and each one plays a huge part in the finished product—that means what comes out of your tap that can make or break your cup of joe.

water temperature for coffee

Ideal Water Temperature for Coffee

How hot your water is—and how hot your water stays—plays a big part in how good your brew tastes, so it’s important to know just how much heat you’ve got going on in your kettle. Ideally, coffee should be brewed with water that is somewhere between 195–205 degrees Fahrenheit, and even better if you can keep the temperature stable between 200–203 F or thereabouts.

Boiling water—actually any water that’s between 208–212 F—will pull extra bitter compounds out of your ground coffee, and can leave you with a too-strong, ashy, and dry cup that is simply unpleasant. Too-cold water, anything dipping below 190 F, for instance, will not be aggressive enough to extract some of the sweet-making flavors that balance the rest of the coffee’s compounds, and you’ll wind up with a sour, astringent cup—not to mention lukewarm. (Note that this is not the case for cold brew because the cool water in that method has a long time to extract flavoring material, where with most hot preparations the water only has four or five minutes to do the deed.)

Temperature-controlled electric kettles are the dream-come-true in this case, then, as they allow you to not only see when the water is at the perfect temperature, but they will hold the water there as well, giving you a nice and even extraction. If you don’t have an electric kettle, counting down 40 seconds to a minute after boiling should put you in just about the right range to brew, or you can invest in a very simple thermometer to check yourself before you wreck your morning.

coffee to grounds ratio

Coffee Grounds to Water Ratio

Aside from extremely concentrated coffee drinks like espresso, the majority of what we pour into our mugs is actually mostly made up of H2O: In fact, the ideal coffee-to-water ratio in the finished beverage is close to 2 percent coffee concentrate and 98 percent water. We need the water in order to dilute the potency of what dissolves from our grounds, which makes it especially important when we’re dealing with coffees that have very intense or even very fine and delicate flavors.

Water Quality

If you’ve ever wondered why coffee brewed at the café always tastes better than the coffee you make at home—even when you buy a bag of the same beans to bring home with you—the answer might actually be in the water. Most cafés and restaurants have high-tech and customized water-filtration systems that can remove impurities, or can even strip the water down to its basic elements and re-infuse a special cocktail of minerals and salts to the distilled result, in order to create a highly specialized brewing solution that is perfectly engineered to complement and not contradict the coffee they’re making.

While you might not have a fancy-schmancy reverse-osmosis system in your own kitchen, you can manage your water quality and significantly improve your brews with just a few tweaks to your liquid ingredient.

If you use filtered water to brew coffee, be sure that it’s not distilled: Most electric kettles can actually be damaged or destroyed by totally pure water, and maybe even worse, coffee brewed with distilled water tastes objectively horrible, way too strong and soul-crushingly bitter. Instead, aim for still spring water.

Always start with cold water in your kettle, rather than using pre-boiled or hot water from the tap. Not only is it more common for cold water to be filtered, but it also prevents too much evaporation during the boiling process—evaporation will lead to mineral deposits and scale build-up in your kettles, which will contribute a taste (and be a royal pain to clean up) over time.

Also, be sure to clean your kettles after using them, with a scent-free and non-abrasive cleaner such as a coffee-machine specific cleaning product made of citric acid or baking soda. You can also use a descaling solution to help keep your coffee makers and kettles working efficiently. Avoid using lemon juice or vinegar, as they leave a very strong scent and flavor behind, and don’t ever use bleach.

* Don’t store your kettles with water in them, to prevent rust—which will also leach into your coffee and leave a flavor behind, in addition to just being unattractive and kind of gross.

adjustable temperature pour over kettle

Water Delivery

You know how the key to good style is focusing on how you do, rather than what you do? Well, pouring water into coffee can be something like that: Anybody can dump a bunch of hot water onto grounds, but doing so won’t result in a top-notch cup. Instead, being intentional and having control over the addition of hot water will have a surprising impact on flavor and extraction rate, and for some brewing methods it’s imperative to be precise.

Agitation is the term that coffee professionals use for both the feeling we get when customers don’t tip, and also the kind of turbulent movement that happens during the brewing process as hot water and grounds are kind of swirling around getting to know each other.

In some brewing methods, controlling this agitation is less of a concern for you as a home barista: For instance, when you’re making a French press, there’s a lot of swirling and movement happening when you first pour the water into the pot, and then a little more toward the end when you depress the plunger, but otherwise the water and coffee just kind of chill out together—you don’t need to worry about it. However, when you’re making a pour-over, you don’t want to just willy-nilly dump water into the filter and kick up a lot of motion and fuss in there: You want to add the water in a delicate and gentle way, more like skimming stones on a lake than dropping rocks off a bridge. A graceful-looking gooseneck kettle is your best tool for this process, as the delicate pour spout not only allows you to direct the flow of water, but the fact that the spout pulls from the bottom of the kettle absorbs some of the turbulence that happens naturally when you dump from the top. (Added bonus: The water at the bottom of the kettle stays hotter longer, because it’s not as exposed to air and it also has the insulation of the rest of the hot water on top of it.)

The next time you brew, make sure you pay as close attention to the water as you do the magic beans that complete your favorite morning indulgence, and you’ll probably discover that the better both of your ingredients are, the happier your mouth will be.

Plus, learn how to store coffee so it doesn’t go bad, how to make your own latte art, or cook up one of these recipes using leftover coffee.

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By Erin Meister

Erin Meister is a freelance writer for OXO. She is a specialty-coffee professional with 15-plus years as a barista, café manager, wholesale account representative, speaker, and educator; she currently sells green coffee for the Minneapolis-based importing company Café Imports. You can also hear her on weekly episodes of "Opposites Extract: A Debate Podcast about Coffee," available on iTunes.

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