Home › Home & Kitchen › Kitchen & Dining › Coffee, Tea & Espresso › Pour-Over Drippers How to Bloom Coffee Published: July 9, 2026 · Updated: July 9, 2026
Photo: Michael Browning CC0 1.0 Source
To bloom coffee, start your pour-over by wetting the grounds with about twice their weight in water, then wait 30–45 seconds before continuing — you'll see them swell and bubble. That's trapped carbon dioxide escaping from fresh coffee, and letting it off first lets the water soak the grounds evenly for a sweeter, more even brew.
Recommended Wet the grounds with ~2× their weight in water, wait 30–45s for the gas to escape, then brew on — Freshly roasted coffee holds carbon dioxide, and when hot water hits it the gas rushes out, foaming up and pushing water away from the grounds so it channels past instead of soaking through. Blooming defuses that first: at the start of a pour-over, add just enough water to wet all the grounds — roughly two to three times the weight of the coffee, so about 40–60g of water for 20g of coffee — and no more. Give it a gentle swirl or stir so every ground is saturated, then wait while it 'blooms', puffing up into a dome and releasing bubbles, for about 30–45 seconds. Then carry on with the rest of your pour in stages. The payoff is a more even extraction and a sweeter, cleaner cup, because the water can now flow through evenly rather than around pockets of gas. The bloom is also a freshness gauge: lots of vigorous bubbling means fresh beans, while flat, lifeless grounds suggest stale coffee that has already lost its gas. Use water just off the boil (around 92–96°C), and if the bloom overflows the filter, you've added too much water — cut back next time.
