Brewing.

Weigh your coffee and water, note your grind setting and keep a record of the result. Change one thing at a time. A repeatable method makes it easier to understand what changed in the cup.

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Starting recipes.

Brewing at home: weigh, grind, note ›

Geisha Colombia: a V60 starting recipe ›

Measure your brew.

Use a scale that reads in grams, a timer and a grinder. The brew ratio compares the weight of the coffee with the weight of the water. For filter and immersion brewing, “water” means the water added during brewing, excluding water used to rinse or preheat. For espresso, the brew ratio uses the weight of the espresso in the cup.

Espresso, by its heritage definition.

The heritage definition of espresso by the Specialty Coffee Association of America (SCAA): 25–35 ml from 7–9 g of coffee, at 90.5–96.1 °C and 9–10 atmospheres. In a 2017 survey by the Barista Guild with Specialty Coffee Association (SCA) Research, 93 % of the baristas who answered said their espresso is a double.

Grind.

Grind just before you brew: ground coffee loses in minutes the carbon dioxide that whole beans lose over weeks, the SCA writes. Change the grind in small steps, one brew at a time, and note each setting.

A grind is a spread of particle sizes. The SCA’s standard for home filter grinders asks that, on at least one setting, less than 18 % of the grounds be finer than 0.6 mm. A grinder can also hold back a little coffee: the standard allows no more than 3 g to stay inside after ten 60 g doses.

In a 2016 study in Scientific Reports, colder roasted beans ground to a smaller mean particle size, with a narrower range of sizes.

A test for machines, not recipes.

The SCA’s standard for electric home filter brewers tests machines, not recipes. The coffee bed must reach 90–96 °C once a third of the water has been sprayed on, and stay in that range until brewing ends. Basket shape changes the test grind: cone-shaped baskets are tested with a finer grind than flat-bottomed ones.

Taste and adjust.

Taste the coffee before making a change. Keep a note of the result and change one thing for your next brew.

Strength and extraction.

Strength is how concentrated a brew is, measured as total dissolved solids (TDS). Extraction yield is the share of the dry coffee that ends up in the drink. In 2023, researchers at UC Davis, working with the SCA’s Coffee Science Foundation, published a new Coffee Brewing Control Chart that maps flavour attributes across both. In a UC Davis study of filter coffee, higher strength went with less perceived sweetness. Stronger brews also tend to taste more bitter, the SCA writes.

In another study of filter coffee, 118 people who drink their coffee black tasted brews of different strengths and extraction yields. Their preferences spread over a wide range.

Temperature works through extraction. In research supported by the SCA, tasters could barely tell apart drip coffees brewed at 87, 90 and 93 °C once their strength and extraction matched.

Cold brew, like for like.

In research for the SCA’s Coffee Science Foundation, cold brew tasted slightly more floral, and less bitter and sour, than hot brew served cold at the same strength.

Water shapes the cup.

Water is an ingredient in every cup. Its mineral composition and buffering capacity can change the result, even when the coffee, grind and recipe stay the same.

Minerals. Calcium and magnesium contribute to hardness and can interact with coffee compounds. More minerals do not automatically make a better cup.

Alkalinity. This is water’s ability to neutralise acids. High alkalinity can soften a coffee’s brightness; low alkalinity leaves more of its acidity perceptible. The right balance depends on the coffee and brewing method.

TDS. Total dissolved solids describe how much dissolved material the water contains. A single reading in parts per million (ppm) does not reveal its mineral composition, hardness or alkalinity. These are different measurements.

Choose your water.

Start with fresh drinking water that tastes clean. Choose treatment for the water you actually have: some filters reduce chlorine taste while retaining minerals; others also reduce carbonate hardness. “Filtered” alone does not describe the result.

For bottled water, read the mineral analysis rather than choosing by brand or price. Calcium, magnesium and bicarbonate are useful clues. Bicarbonate in mg/L is not the same measurement as alkalinity reported as CaCO₃.

Keep the coffee, grind, dose and brew recipe fixed when comparing suitable waters. Taste the cups as they cool, and keep a note of the water you used. This gives you a clearer comparison.

Protect your equipment.

Water that tastes good in filter coffee still needs to meet your espresso machine’s specifications. Scale formation and corrosion depend on water chemistry and operating conditions.

Check hardness and alkalinity separately, and follow the manufacturer’s limits for pH, chlorides and other parameters. Chloride is different from the chlorine that can affect water’s smell or taste. Do not use untreated distilled or reverse-osmosis water in a machine unless its instructions specifically allow it.

Berlin’s tap water is generally hard. Check the Berliner Wasserbetriebe analysis for your postcode, then choose suitable treatment and maintain it as instructed. These are regional data, not a measurement at your tap.

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