Calculadora de Receita de Água para Café (SCA + DIY)
Monte a água para café a partir de água destilada ou de osmose reversa, mais sal Epsom e bicarbonato de sódio, para atingir as metas de dureza da SCA.
Calculadora
Dentro da meta
GH 68 ppm e KH 40 ppm ficam ambos dentro das faixas da SCA (GH 17–175, KH 30–70). Esta é uma água de preparo equilibrada e favorável à extração.
Mais fácil: faça um concentrado
Doses diretas são inferiores a um grama e difíceis de pesar. Em vez disso, dissolva 8.37 g de sal Epsom + 3.36 g de bicarbonato de sódio em 1 L de água destilada (um concentrado-base). Depois adicione 20 mL de concentrado por litro de água de preparo — um litro de concentrado trata cerca de 50 L.
Água só com bicarbonato de sódio adiciona sódio: cerca de 0,46 mg/L de Na por ppm de KH (≈ 18.4 mg/L aqui). Para água com baixo teor de sódio, use bicarbonato de potássio em vez disso.
As metas de GH são indicativas — existem duas tabelas da SCA (o padrão de 2009 gira em torno de 68 ppm; gráficos posteriores abrangem 50–175 ppm). Ajuste ao seu gosto.
Sobre esta calculadora
Water is most of what is in your cup, and its mineral content changes how coffee extracts and tastes. This calculator builds brewing water from a clean base — distilled or reverse-osmosis (RO) water, which is almost mineral-free — by adding two cheap minerals: Epsom salt for general hardness (GH) and baking soda for alkalinity (KH). Set your batch size and your GH and KH targets and it returns the grams to add, plus an easier make-ahead concentrate, and tells you whether you have hit the SCA water windows.
Como ler seus resultados
GH (general hardness) is the magnesium and calcium that drive extraction; KH (alkalinity, also called carbonate hardness) is the buffering that tames acidity. The SCA targets are GH ≈ 68 ppm and KH ≈ 40 ppm (both as CaCO₃), with a total dissolved solids (TDS) target around 150 ppm and pH near 7.0. Because the direct doses for a 1 L brew are well under a gram, weighing them is fiddly — so the calculator also gives a stock concentrate you dissolve once and then dose by the millilitre.
Como é calculado
Epsom salt (MgSO₄·7H₂O) raises GH by 406 ppm per gram per litre; baking soda (NaHCO₃) raises KH by 596 ppm per gram per litre, both expressed as CaCO₃. So grams = target ppm × litres ÷ factor. The concentrate scales the per-litre dose up by a fixed factor so it is weighable, and the dose-per-litre is the inverse of that factor. Baking soda also adds sodium — roughly 0.46 mg/L of Na for every ppm of KH.
Exemplo prático
1 litre of distilled water, targeting the SCA defaults: GH 68 ppm and KH 40 ppm.
Add about 0.17 g of Epsom salt and 0.07 g of baking soda (≈ 0.23 g total). Easier: dissolve 8.4 g Epsom + 3.4 g soda in 1 L of distilled water as a concentrate, then add 20 mL per litre of brew water (one litre of concentrate treats ~50 L).
Perguntas frequentes
Why start from distilled or RO water?
Distilled and RO water are almost mineral-free, so the minerals you add are the entire recipe and the result is repeatable. Tap water already contains varying minerals, so adding more on top is guesswork unless you have a water report.
Why a concentrate instead of dosing the dry powders?
For a single litre the doses are a fraction of a gram, which most kitchen scales cannot weigh accurately. Dissolving a larger amount once in a stock concentrate lets you dose precisely by the millilitre for every future batch.
Is baking soda the best source of alkalinity?
It is the cheapest and most available, but it adds sodium — about 0.46 mg/L of Na per ppm of KH. If you want to avoid sodium, potassium bicarbonate raises KH the same way without it.
My GH target looks off compared to another chart — why?
There are two SCA reference tables. The 2009 standard centres GH near 68 ppm; later charts allow a wider 50–175 ppm band. Both are acceptable starting points — treat GH as indicative and dial it to taste.
Fontes
Revisado pela equipe do YouCalc · Última revisão
Notou algo na tradução, no cálculo, ou quer fazer uma sugestão? Conte para a gente.