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David Schomer’s Blog | Cutting-edge espresso technique and equipment review

Espresso Theory-Water Purity and Mineral Content

Dear Reader,


Let’s revisit a factor I have not written up for 15 years.  Water purity and mineral content.  For about a year in 2006 we had water formulators to “tune” our brewing water to a specific mineral content.  The effect on the flavor of our coffee and tea was sublime.  But what is the best water for espresso,  saturation method coffees, and tea?  In my opinion, it is water with a TDS of about 150ppm.  Ok, that is a mouthful…TDS means total dissolved solids and is also refered to as mineral content, and ppm means parts per million. (Water tuned to this mineral content will have a slight oily taste in the back of the mouth when you drink it. Water in most E. Coast cities will weigh in higher, around 350ppm and up, and features a very oily feel and taste and usually will be filtered with a reverse osmosis filter just for drinking.)

As I said we worked with this water for about 12 months in 2006 and 2007, using a very sophisticated mixing computer and mineral additives to formulate the mineral content in our water at all our bars..  Unfortunately, the company was owned by a brilliant scientific visionary with no idea how to build a company to service these high tech gizmos and eventually we had to remove them.  But during this time I discovered many characterisitics about espresso and tea brewed with this water that I will share with you.


Really the effect on espresso and tea was remarkably similar.  Let’s make a comparison with Seattle water that has been run through a carbon filter only and has a mineral content year round of about 50ppm TDS.  First the flavor of the espresso lacked a sharp point over the top of the pallette that is similar to making espresso on equipment that is new, or recently cleaned with detergent without seasoning the machine. Literally it is metal molecules that leach out of the boiler (or teapot) when water is heated up and it tastes metallic.. Molecules leave the metal through osmosis because of the low concentration of minerals present in the water. (This water tastes great for drinking as does most mountain states water. In Vancouver BC the water often contains as little as 10ppm of TDS.) So the flavor was softer with no harsh point. The same was true for macha, the concentrated green tea made with only the baby tea leaves and whisked to a foam during many tea ceremonies throughout Japan. The macha tasted sweeter with no harsh point.

The other effect on the flavor of espresso was to open up a multi dimensional layering of distinct flavors. I could taste the blueberry from the Harrar, caramel, dark chocolate, honey, anise, and “hoppiness” from the Brazil, very clearly, stacked up on my tounge in distinct flavors that were much easier to perceive than espresso brewed on 50ppm water.   This was quite remarkable and made cupping a very clear affair even using the espresso method to sample coffees.  (….and I struggled for months before ripping out these systems..floods, lack of supplies, it was a plauge of amateurism and marks the first time Vivace has ever backed off on improving a factor.)

A similar effect took place with the macha, bringing out a rich “umami” with a note in it, believe it or not, like a great steak.  The flavor of the macha was layered as well like a springtime breeze with underlying richness.  (Interestingly enough, my friends favorite old iron tea pot produced the desired TDS of about 150ppm when Seattle water was boiled in it for a few minutes. I got the biggest kick out of that.  The old tea masters in Japan had intuiitively chosen this style pot long before the modern era,  as creating the best tea, or perhaps it was a lucky shot.)


So, how to you measure your water?  get a  TDS meter from the Myron L Company like the one pictured below. It is called an Ultrameter II and I recommend picking up the calibrating fluid shown as well.


How do you tune your own water?  For areas like Western Washington, that have pure mountain runoff water with a very low TDS I do not have an answer.  I am hoping someone knows of a water tuning computer made somewhere that is supported by a professional company.  If you do please e-mail me at attn: David.

For most of the country where the mineral content is high, I would filter the tap water through reverse osmosis, producing literally zero ppm of TDS,  and then re-mix to the desired mineral content.

I consider water formulating a final factor to bring into an espresso program that is already very tight.  The effect, while delightful, is subtle on espresso, perhaps more noticeable for saturation coffees and tea.