The Lowdown on Distilled Water

A common inquiry we receive is in regard to the type of water customers should use in their coffee making equipment. Some folks think that distilled water will be their best bet, as they won’t have to worry about scale build up or performing descaling procedures for the life of the machine. While there seems to be as many supporters as there are detractors regarding whether or not it’s healthy for the human body, we do know that distilled water is not healthy for your machine. Seriously!

First up, let’s talk about your equipment. Putting water that has a lack of ions or mineral content through equipment that is basically composed of minerals (stainless steel, copper, nickel, brass, etc.) means the water will take that opportunity to take on ions from the surrounding space, contributing to a slow breakdown of those materials. It will essentially leach minerals out of the metal components and degrade the machine’s performance over time. Additionally, there are several models of machines on the market (such as the Rockets) that use a minor electrical charge to determine if there is water in the reservoir. If there aren’t enough minerals in the water to conduct that charge, the machine’s sensor will report that the reservoir is empty.

Now, let’s talk about the coffee. The Specialty Coffee Association of America performed extensive testing and found that the ideal mineral balance is 150 parts per million (ppm). Coffee produced with water that contains this level of hardness is better balanced and a smoother cup. A lower mineral content allows for too much available space, often resulting in an overextraction and a bitter flavor. Conversely, water with a higher mineral content won’t have enough available space, so coffee will be underextracted and possibly more sour. As distilled water has hardly any mineral content (roughly 9ppm), using it for coffee preparation will result in a bitter cup.

We often say that you should use water that you like to drink to make your coffee — after all, coffee is over 98% water. Another option is to use softened water, which encapsulates the minerals, maintaining their structure within the water while prohibiting their ability to adhere to internal components. This can give you the best of both worlds: A smooth and balanced cup of coffee while also reducing the overall maintenance for the life of the machine.

4 comments for “The Lowdown on Distilled Water

  1. John Parkinson
    April 7, 2012 at 10:28 am

    I use distilled water as part of the cleaning process (after running Cleancaf or Durgol) through my Technivorm. Now I wonder if this is also a bad idea. I use bottled mineral water for coffee. Yum.

    By the way, really enjoy the videos!

    • Kat
      April 9, 2012 at 9:35 am

      Well, I would suggest that you rinse with the mineral water; even though you’re using a minor amount of distilled water in the system, it will slowly leach minerals from the metallic internals over time … and could have a minor adverse impact on the machine’s lifetime performance.

      - Kat

  2. Keith Wonderly
    September 18, 2012 at 6:04 am

    I have to disagree with the degradation theory represented in the blog. running distilled water through components will not rob ions from those components. Water likes to be balanced in its natural state and this means that distilled water, which is low on ions, will try and add ions to itself to achieve that goal. the distilled water will grab ions from everything it touches that can be dissolved or absorbed. The components inside your coffee maker are not made from anything that could be dissolved or absorbed. Heating tubes are generally constructed from aluminum tubing, and the tubing and misc valves are typically constructed of ABS plastic. neither could be dissolved by the distilled water.

    • Kat
      September 19, 2012 at 9:07 am

      Hi Keith -

      Thanks for sharing your opinion. The majority of machines we sell actually feature copper or brass boilers and distilled/deionized water does pit them over time, as well as having an adverse affect on heating elements. I agree that distilled water won’t have an impact on waterworks that are largely constructed of plastic, but for the majority of the home and commercial machines we sell, it does. Also, it doesn’t produce a balanced cup of coffee so we can’t recommend using it for that reason alone :D


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