Water for coffee / by Bryan Hibbard

There are so many topics that I could write about out of CoffeeFest, but I think one of the most important is water quality. Brewed coffee is 99% water, so the quality of your water is very important. 

I got the opportunity to attend a session with the guy who wrote the book on water standards for coffee (his company is Global Customized Water). Literally, the Specialty Coffee Association of America asked him to write a handbook detailing water quality standards for coffee cupping. This is so that every cupping lab around the world can be using roughly the same water when analyzing coffee.  In case you are curious, here is the website that lays out the water standards.

At the meeting, I sampled an experiment that Global Customized Water had set up. They had three Chemex brewers all with the same coffee brewed at the same ratio. The only difference was the water. The first batch was brewed with distilled water, it was overwhelmingly bitter and lacked aroma. The second batch was simulated tap water (about 400 ml/L total dissolved solids), the aroma was much better, but the coffee was again pretty bitter and there was a noticeable mineral taste along with the coffee taste. The third batch was formulated for optimal extraction and it was the clear winner in terms of flavor and aroma.

I have been using water that has been filtered through a reverse osmosis system for coffee by the cup at the market. It turns out my water was too pure. It actually needs 150 mg/L of total dissolved solids to properly extract the coffee. So, I am now using a mineral formula from Global Customized Water (a combination of food grade sodium, potassium, and calcium) to supplement my reverse osmosis water. The difference is quite obvious to me. The aroma is now much richer and the flavor is more round. Our coffee at the market is good, but I am always happy when I can find a way to make it even better!

What about your coffee at home? My best suggestion is to use an inexpensive carbon filter (such as Brita or Pur, or the one in your fridge) on tap water. This leaves enough minerals behind in the average city water to be within the acceptable range for coffee brewing. If your water is especially bad, then you may have to employ other methods. If you like playing with chemistry, buy a total dissolved solid meter and play with various filtering options until you get close to the 150 mg/L standard. Whatever you use, make sure that the filter has removed the chlorine from municipal water as even a miniscule amount of chlorine can affect coffee flavor.

What should you not use? Softened water, distilled water, natural spring water, chlorinated tap water. My father-in-law has a water softener as well as a very nice reverse osmosis filtration system. It makes great drinking water and cleaning is a snap because there is no hard water build-up. But it makes weak coffee. He noticed a big difference when he started using water with more mineral content.

I am constantly striving for the best quality coffee at home. You want an amazing cappuccino, go to a coffee shop with a fabulous $15K espresso machine. You want the best dang cup of brewed coffee you can get, buy freshly roasted beans and brew at home. With the right water, you are one step closer to the perfect cup.