The Boring Reason Your Coffee Tastes Flat

It is the water. It is almost always the water. Coffee is 98.5% water, and if your tap water is soft and neutral, your bright Ethiopian will taste like a rumor of itself; if it is heavily chlorinated, no roast profile on earth can save it.

The fix is boring and cheap: a basic carbon filter, or mineral packets designed for coffee, or — the house answer — a 50/50 mix of filtered tap and third-wave mineral concentrate. Aim for roughly 80–120 ppm total hardness and you have solved more than half of every bad-cup mystery we get asked about at the bar.

We tested this at the counter for a month, brewing the same coffee two ways and making guests guess which cup was the filtered one. Forty-one of forty-four guessed right. The other three were probably being polite.