The most important ingredient in great coffee is not the coffee bean nor the ground coffee nor how you make it. It’s the water.
The Specialty Coffee Association (SCA) and other sister organization all over the world have done a lot of research into the effect of water on a good cup of coffee and all have come to very similar results:
- no chlorine
- low calcium & sodium
- neutral pH
The best water for your coffee is sometimes what comes out of the tap, if you live in a couple of very lucky countries. For most people, a water filter is highly recommended, or the use of bottled (mineral) water. But beware: mineral water can also ruin your coffee no matter what you use or how you make it.
Pay attention to the little label on the side of the bottle and look for this:
- 6.5 < pH < 7.5
- 75 mg < dissolved minerals < 150 mg
- low sodium (Na)
On this island, Volvic mineral water is the best we have been able to find. Evian is among the worst.
Now some may want to use water cleaned through reverse osmosis, because it is the cleanest. But that water is so clean it lacks important aspects for your body to be able to taste the coffee properly. The pH is fine but there is hardly any calcium or sodium and it completely lacks the important dissolved minerals. So while it may make a fine coffee, you can tell from the crema layer in an espresso or filter brew that the water is not good enough.
See also No Pressure Coffee blog