Water affects many aspects of espresso, from the coffee’s taste to the longevity of brewing equipment. Achieving great coffee while protecting the espresso machine requires a balancing act—a challenge that water treatment specialists and great coffee bars are taking on together. There is a simple truth about brewing espresso that you might not want to hear. The fact: most coffee machine maintenance issues are caused by water, the one substance that touches nearly every part of the machine.
Minerals in water are the culprits, coating the inner workings of the machine and impeding its performance. The more minerals the water contains, the harder or more damaging it can be. Particles will build up on—or scale—pumps, boilers and valves.
But minerals are also what make coffee taste good, carrying its body and aroma to the palate. Ideally, brewing water contains certain amounts of specific kinds of minerals.
So coffee flavor is priority one, while brewing equipment must simultaneously be guarded from damage. All espresso machines must be occasionally descaled. Since good brewing water requires mineral content, the key is to minimize the need to descale by removing the most damaging minerals while keeping enough of them in the water to enhance the coffee’s taste.
The Specialty Coffee Association’s technical standards committee recently updated and published standards for brewing water. Acceptable brewing water must have the following characteristics:
- No odor
- Clear of color
- Free of chlorine, iron and sulfur compounds
- TDS: 150 ppm
- Calcium: 3-4 grains
- Alkalinity: 40 ppm
- pH: between 6.5 and 7
- Sodium level: 20 mg