That coffee sitting in front of you is deceptively simple. Sure, it’s just a solution of mostly water, but that water is responsible for the variable amounts of fats, acids, and other tasty solubles that make that cup amazing or abhorrent.
Consider that cup, but in your mind, rewind time so that water pulls up against gravity, back through the grounds, returning to just water.
If you’re picturing what I’m picturing, you’ve got clear, hot water sitting above dry grounds. That water dictates how much coffee will dissolve into that solution you end up drinking (ok, now hit the play button of your mind to watch the water slip through the grounds).
It won’t be necessary for you to review your entire Periodic Table of Elements, but it’s worth reminding you that different elements (therefore chemicals) react differently with each other. Suffice to say that the chemical composition of your brewing water will drastically change your coffee's flavor. That's why we're making a multi-issue post establishing a scientific test to determine the best and worst ways to brew your coffee.
And by scientific, I mean literally use the scientific process: Question, Hypothesis, Experiment, Results, and Analysis.
Question: We know we want to use water to brew coffee (we all went through that Idiocracy phase of trying to brew with Gatorade, but water did turn out to work better), but the real question is “what level of filtration is best for brewing coffee?”
Let's be more specific to home brewing, though. We'll create an experiment to explore this question: “Is it best to brew coffee with water from the tap, through a generic charcoal filter, through a reverse osmosis system, or through an RO system that has some particulate matter reintroduced?”
Hypothesis: 98% of quality coffee shops use RO water that’s got a certain amount of particulate matter reintroduced, so I’m going to assume that if I taste all those different filter-methods of water, I bet the RO+some particulate matter will taste best.
Experiment: Over the next week, I’m going to brew up a Kalita of the same coffee using the same ratio of water and coffee, all ground the same, using each of the aforementioned kinds of water. I'll record extraction of coffee from each brew using a refractometer after each brewing as well as consider what my taste-buds and nose tell me.
Check in Monday (October 16th) to see the results of the test. We'll post the analysis of those data-points so you can optimize your coffee experience.
We also encourage you to join us in this experiment. It doesn't matter if you use a Kalita, french press, Clever, AeroPress, or even a syphon... as long as you're consistent, try duplicating this experiment and keep notes about how it tastes.
It would be bizarre if any of your at home have your own, personal refractometer, but you can keep notes (if you want, use this form) about your sensory experience with each coffee.
So you've got a week to do your own experimenting. Just don't forget to check in with us in a week to see if you agree with what we've found! See you soon, and happy sciencing!