How Water Quality Impacts Coffee Extraction

To the average home brewer, the quality achieved in a coffee shop can seem too expensive to accomplish. In some ways (primarily as we consider the cost of high-quality espresso machines), this is true. But in the world of filter coffee, or manual pour-overs, there are many inexpensive areas of focus that the home brewer can leverage to increase the quality of their morning cup. The first step, of course, is selecting a high quality fresh roasted coffee for your home brewing. Perhaps the next most important step, is assessing your water quality. 

Water Quality as a Brewing Variable 

If you are brewing coffee at home, you may have spent years perfecting your ratios, grind size measurement, manual pour-over technique, and water temperature. You have probably thought through variables like what filters to use, what dripper you’d like to purchase, and how to keep your beans fresh (read more about that here). However, there’s a secret ingredient that often gets missed, and it needs a lot more attention than you’d think. Your filter/drip cup of coffee is 98% water and only 2% dissolved coffee solids, meaning your favorite cup of coffee can only be as good as the water you use to brew it. For most of us, that means that we likely need to figure out some sort of filtration for our tap water, —unless you’re blessed with pre-installed water softeners or exceptionally high-quality tap water. 

What Makes Good Water for Coffee Brewing? 

There are two primary concerns with the water you are using to brew your coffee at home: mineral ions and alkalinity. The mineral ions that contribute to your ability to extract coffee flavors well are magnesium and calcium.  These minerals, along with others, determine the water's “hardness” or “softness.” Water that is too hard, will lead to coffees that taste bitter and muddy with high levels of extraction and is generally why you want to avoid using water straight out of the tap.  However, it's important to understand that the solution isn't as simple as using distilled water—water so filtered and purified that none of the naturally occurring minerals are left intact. These minerals play quite an important role in the extraction of flavor compounds.  

What is the Right Way to Filter Water? 

There are many ways to achieve a filtered water without stripping the water of the necessary minerals to extract flavor well. Start by learning more about your area’s tap water and what kind of minerals are present.  A good rule of thumb is that if your tap water tastes clean, a simple home filtration system should do the trick for making pretty good coffee. If your tap water is harder, you may benefit from something a little more robust. If you are interested in getting technical with your water for brewing at home, you can re-mineralize distilled water with a product specifically designed for coffee brewing. These products are popular among the specialty coffee industry and have unique blends of minerals to assist with ideal amounts of extraction.  

What are the Specialty Coffee Association’s Recommendations? 

The Specialty Coffee Association, or SCA, is a great resource for learning more about the standards for brewing high quality coffee. As far as water quality, the SCA recommends clean water with no odors, no evidence of chlorine, and a pH between 6 and 8. They call for a calcium hardness between 50 and 175 ppm and an alkalinity between 40 and 70 ppm. All this information about your local tap water can be found on city websites so you can learn what you might be up against.  

For more information on the SCA recommendations, checkout their water standards here: https://sca.coffee/heritage-coffee-standards!  

Where to Start  

If you are interested in learning more about how your water quality might be affecting your cup of coffee, a great first step is to try brewing coffee with both filtered and tap water at home and seeing which you prefer. Doing so might tell you all you need to know. Your second step is to check out city reports of your local tap water and see what sort of filter would optimize your water at home. Finally, consider utilizing specialty products like mineral packets for your coffee brewing water.   

The relationship between water quality and coffee extraction is an evolving topic, with new research constantly emerging in the industry. We hope this guide has shed light on how water affects your pour-overs at home and helps you brew better coffee at home. Even small changes in water quality can have a significant impact on your coffee's flavor and aroma, so start exploring today!