A water recipe starts from distilled or reverse-osmosis water — which has essentially nothing in it — and adds a measured mineral content back.
Why bother
Tap water is whatever your utility supplies, it varies seasonally, and it is rarely in the ideal range for coffee. A recipe removes that variable entirely and lets you brew the same water in Seattle and in Atlanta.
How it works
Two concentrates are typical: one supplying magnesium and calcium (hardness), one supplying bicarbonate (buffer). You dose each into a known volume of distilled water.
Commercial sachets — Third Wave Water, Lotus, Aquacode and others — do the same thing pre-measured.
What it changes
On light-roast filter coffee, audibly: more defined acidity, more separation, more sweetness. This is why competition brewers all use recipes.
On espresso with milk, very little. The milk covers it.
The costs
Money. Distilled water plus concentrates is more expensive than a filter pitcher.
Effort. Every brew needs made-up water.
Not for machines with sensors. Some espresso machines detect water by conductivity and will not register very pure water. Check before committing.
The honest starting point
Filter your tap water first, and find out its hardness. If you are in the useful range, a recipe buys refinement. If your water is extreme in either direction, it buys a genuine fix.
Last reviewed 30 October 2026