The Water Temperature Guide

Why Boiling Water Ruins Coffee

Water at a full boil (100°C/212°F) is too aggressive for almost every brewing method. It scorches coffee grounds, rapidly extracting bitter, ashy, and astringent compounds before the sweeter, more delicate flavours get a chance to dissolve. The fix is simple: after boiling, let your kettle rest for 30–60 seconds off the heat before pouring — enough time to drop into the ideal 90–96°C window.

Why Cool Water Under-Extracts

Water below roughly 88°C struggles to dissolve coffee's flavour compounds efficiently, especially the sugars and oils responsible for sweetness and body. The result is sour, thin, "underdeveloped" coffee — the opposite problem to scorching, but just as damaging to the final cup.

Roast Level Changes the Ideal Temperature

Darker roasts are more porous and extract faster, so they often benefit from slightly lower temperatures (90–93°C) to avoid emphasising bitterness. Lighter roasts are denser and extract more slowly, so they often need the higher end of the range (94–96°C) to fully develop their acidity and sweetness.

No Thermometer? No Problem

If you don't have a temperature-controlled kettle, boil water and let it sit uncovered for 30–45 seconds — this reliably drops it into the ideal range for most brewing methods at sea level. Use our ratio calculator to pair the right temperature with the right dose, and our Brew Doctor if your coffee still isn't tasting right.