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Science of Water and Coffee

The Science of Water & Coffee

Your typical cup of coffee is made up of 98% water, so water definitely has an impact on what you're drinking.


This Cafe@Home, we discuss the effect of water on the flavor of your coffee. But how does water make a difference and what should you do about it?

It stands to reason that if your water doesn't taste good, your coffee won't taste good. There's much more to it than that.

Queue up this week's acoustic Spotify playlist and learn more about how the hardness, pH, TDS, and temperature in your water affects how your coffee taste.

☕ We all want good tasting coffee! ☕

☕ Do you like the taste of your water? ☕

If your water doesn't taste good, your coffee won't taste good. That makes sense. But that's not all. The hardness of your water, meaning how much magnesium and calcium are in it, also affects your coffee. As does the pH. Both of these elements can determine how much of the coffee flavor is extracted from the coffee grounds as well as how the oils actually taste.

So, what's the best alternative for brewing your coffee? Should you use tap water, filtered tap water, bottled water? Queue up this Spotify playlist and learn more about how the hardness, pH, TDS, and temperature in your water makes your coffee taste.

Great tasting coffee starts with the water. Yes, the beans you use are important, but with bad tasting water, the flavor of your coffee will suffer. After all, like we mentioned above, coffee is 98% water (espresso is closer to 95%). There is a wide range of water options you can use when you make your coffee.

  • water out of the tap
  • filtered water
  • bottled water

But which of these is the best?

There have been studies, both scientific and not so scientific, to determine which water type produces the best tasting coffee.

One study found that the hardness of water has an effect on coffee extraction. A hardness of between 50-80 parts per million seems to be the best. Anything above or below that diminishes the flavor. Subsequently, a hardness level above 80ppm can also damage your coffeemaker.

The same study found that the pH of your water should be between 7 and 8.5. The higher the pH, the more flavor that is extracted, and the better consistency in your coffee.

Finally, they found that the amount of dissolved solids, the TDS, in your water doesn't make a difference.

To break this down:

  • Hardness is the amount of magnesium and calcium in the water
  • pH is the level of acidity or alkalinity in the water
  • Total dissolved solids or TDS is the term used for anything else that might be in the water - salt, chemicals, organic compounds

So, how do you determine which water you should use? Start by having your water tested to find out exactly what you're working with. Also, try tasting the water right out of your tap. If you like the taste, then try it with your coffee. If you don't, try filtering it before brewing. You can also try bottled water. Try different waters to see what you like best.

Though science may have been used to learn more about water and how it affects the flavor of coffee, as we've said before, this isn't a science. How coffee tastes to you is very personal. Find what works for you and use that combination.

☕ Water temperature can also affect how your coffee tastes ☕

How about the temperature of the water? In the past, we've discussed how water temperature can make a difference in the flavor and quality of your coffee.

As a recap, depending on how you are extracting your coffee will determine the temperature. Cold-brew can be made with room temperature water right out of the tap or can be started with hot water to speed the process. When making coffee in a French press or in a pour-over cone, the temperature should be between 195 and 205 degrees Fahrenheit. If you are using a coffeemaker, a percolator, or an espresso machine, it should heat your water to the correct temperature to begin with.

Experiment with your water and determine what works best for you. If you aren't happy with your coffee, make changes. Even if you are happy with it, trying other options won't hurt. You might even find a new combination.