So i've been wanting to talk to everyone about water for coffee for a while, but once I started researching more I went down a large rabbit hole and decided that this is going to be delivered in a 3 part series!
At the beginning it's going to feel like you're sitting in a junior cert science class all over again but it's all vital information.
The water with which we brew our coffee is fundamentally not just water. Chemically, our brewing water is not pure - it contains dissolved minerals, chemicals, and gases, many of which have a noticeable role to play when brewing coffee. While there is certainly more to be learned about specifically how each component affects coffee brewing, we do have a somewhat substantial base of established knowledge about water and coffee already. Practically speaking, the best water to brew with tends to taste and smell quite neutral, so it contributes little in the way of off-flavors to the coffee itself. Scientifically, things get rather more complicated.
Perhaps at worst you have some strange flavors from old metal pipes, an odor of chlorine, or too much calcium or magnesium from hard water. In many cases in the home, you could simply filter that water and be on the right track for brewing coffee with decent to great flavor. If you’re not all that fussy about your coffee and you’re happy with your brewing results, then the chase might end right there.
What's in water, it's just water right?
Hard water is water with which it is difficult to form a lather with soap. The soap forms scum, which is a grey coloured precipitate. The reason soap is not being used as much today is because of this. Modern detergents work with hard water and can form lather easily.
Hardness in water is caused by dissolved Ca^2+ or Mg^2+ ions.
Hardness in water is distinguished by two types; temporary hardness and permanent hardness.
The one which affects our water most for coffee is permanent hardness is hardness in water that cannot be removed boiling. It is caused by the presence of either sulfates. Calcium or Magnesium sulfate (caso4 or mgso4)
Have I lost you yet?
Okay so what the hell does that mean.
Hard water means that there are essentially blockers from you being able to extract all the good stuff from your freshly ground coffee. Think of it like, there's a wall between the water and the coffee, depending on the amount of minerals in you're water, the more or less that wall gets broken down. (i'm also terrible at analogies sometimes)
The Specialty Coffee Association of America has a simple list of standard criteria for brewing water: it should be clean and free of odors, colors, and off-flavors. It should have a neutral pH (neither acidic nor basic), it should have around 150 mg/L of dissolved minerals, including 4 grains of hardness, about 10 mg/L of sodium, and 40 mg/L total alkalinity. While most of us do not own the testing kits needed to see if our desired water is within those parameters, some bottled water options do in fact list some or most of these metrics, and test strips are fairly inexpensive if you’d like to test on your own. The Water Standards are time-tested and generally well accepted, but don’t necessarily align with some of the more contemporary suggestions established by newer research.
If you use crappy water, you’ll end up with some crappy coffee. So what is the answer then? Filtered water? Distilled water? an additive? Where do you even get the best distilled water for coffee? That’s what we’ll answer in part 2.