When we first started getting serious about coffee, we were fascinated by why the stuff in coffee shops tasted so much better than the same beans at home. It is not unlike wondering why restaurant food is better than your own cooking. The spoiler, in that case, is butter.
Plenty of things go into a good cup — the grind, the bean, the temperature — but almost everyone forgets the ingredient that makes up most of it.
Coffee is about 98% water. Once you have actually sat with that number, it becomes obvious that water quality is not a detail. It is most of the drink.
People overlook the water because it seems too ordinary to matter. Ask any serious roaster and they will tell you they have strict rules about theirs.
The three you are choosing between
Tap. Some cities are simply lucky. San Francisco drinks snowmelt from the Hetch Hetchy reservoir on the Tuolumne, up in Yosemite. New York has the Croton, Catskill and Delaware watersheds doing the same job. If you live somewhere like that, congratulations, and stop reading. Most tap water carries chloride and fluoride and whatever your building’s pipes contribute, all of which ends up in the cup.
Bottled. A great many people believe this is the premium option. Much of it is municipal tap water that has been through a filter and into a plastic bottle at a considerable markup. It is also an enormous amount of waste for something coming out of your own wall.
Filtered. This is the answer, and it is embarrassingly cheap. A jug filter costs less than a bag of good beans. Plumb one into the sink if you are committed. The reason the best coffee shops taste like that is, in part, a filtration system you never see.
Do the experiment. Same beans, same grind, same method, three different waters, side by side on a Saturday. It takes twenty minutes and it is genuinely startling.
Fresh beans, fresh water. It only makes sense, really.
