Why Water Matters
While we brew coffee from beans, over 98% of the beverage in your cup is… water. Its mineral composition influences extraction, flavor balance, and the overall perception of the brew. Water that is too soft makes coffee taste flat, while water that is too hard can result in a bitter and heavy brew. This is why baristas worldwide experiment with water as much as they do with brewing methods.
Minerals in Water – Key Roles
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Calcium (Ca²⁺) – affects the body of the brew, can emphasize acidity.
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Magnesium (Mg²⁺) – considered a “flavor hero” – intensifies sweetness and fruity aromas.
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Sodium (Na⁺) – in small quantities improves balance, but it's easy to overdo it.
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Potassium (K⁺) – acts similarly to sodium, with a hint of delicate sweetness.
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Chlorides (Cl⁻) – impart smoothness, round out the flavor.
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Sulfates (SO₄²⁻) – add clarity and sharpen acidity.
Manufacturers, such as Lotus Coffee Water and Apax Lab, offer ready-made mineral salt blends for building coffee water. However, homemade concentrates and recipes, including those created by Barista Hustle, remain popular.
Differences: Chlorides vs. Sulfates
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Chlorides – make coffee fuller, smoother, more “round & sweet”. Ideal when you want to emphasize creamy body.
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Sulfates – emphasize freshness and acidity. Excellent for light-roasted coffees, e.g., Geisha or Ethiopian.
Balance is key – too many sulfates can lead to roughness, while an excess of chlorides can result in overly one-dimensional sweetness.
Mineral Concentrates – Recipes
To precisely and conveniently replicate various mineralization profiles, we first prepare concentrates of individual salts. This allows us to later dispense only small amounts of liquid (e.g., drops from a pipette), which helps achieve a consistent sensory effect. The table below lists the most commonly used coffee water concentrates, along with their impact on taste.
Table 1. Mineral Concentrates (70 ml, mineral purity ≥ analysis grade)
| Concentrate | Ingredient | Salt Amount | Distilled Water Amount | Impact on Taste |
|---|---|---|---|---|
| Calcium (CaCl₂·2H₂O) | Calcium chloride dihydrate | 8.26 g | 70 g | Fullness, body |
| Magnesium (MgSO₄·7H₂O) | Epsom salt | 13.85 g | 70 g | Fruity, sweet |
| Magnesium (MgCl₂·6H₂O) | Magnesium chloride | 11.42 g | 70 g | Fruity, sweet, smooth |
| Sodium (NaHCO₃) | Sodium bicarbonate | 4.72 g | 70 g | Balance, acidity mitigation |
| Potassium (KHCO₃) | Potassium bicarbonate | 5.63 g | 70 g | Sweetness, softness |
Preparing concentrates: weigh out the exact amounts of salts (see table) and dissolve each separately in 70 g of distilled water in a clean dropper bottle. You will get five basic concentrates: Ca, MgSO₄, MgCl₂, Na, K.
Water Recipes
The following recipes are inspired by Barista Hustle kits (e.g., Rao/Perger, Budapest). Sweet Berry, Jasmine Gesha, and Balanced are our own proprietary recipes that we use daily. In creating them, we were inspired by materials from both Lotus and Barista Hustle.
Table 2. Water Recipes
| Profile | Dosage (300 ml) | GH (ppm) | KH (ppm) | Est. TDS (ppm) | Brief Sensory Impression |
|---|---|---|---|---|---|
| Budapest | 2 drops Mg + 2 drops Na | 30 | 15 | 45 | Clear, light acidity, clarity |
| Budapest (900 ml) | 6 drops Mg + 6 drops Na | 30 | 15 | 45 | As above (larger scale — identical ppm) |
| Rao / Perger | 2 drops Ca + 2 drops Na | 30 | 15 | 45 | Balanced, universal (more "classic") |
| Rao / Perger (900 ml) | 6 drops Ca + 6 drops Na | 30 | 15 | 45 | As above |
| Sweet Berry | 2 drops Mg + 1 drop K | 30 | 7.5 | 37.5 | Juicy, fruity; lower KH → more "sparkling" fruits |
| Sweet Berry (900 ml) | 6 drops Mg + 3 drops K | 30 | 7.5 | 37.5 | As above |
| Jasmine Gesha | 2 drops Mg + 2 drops K | 30 | 15 | 45 | Floral, delicate, light sweetness |
| Jasmine Gesha (900 ml) | 6 drops Mg + 6 drops K | 30 | 15 | 45 | As above |
| Balanced | 1 drop Ca + 1 drop Mg + 1 drop Na | 30 | 7.5 | 37.5 | Fullness with preserved clarity; slightly rounded profile |
| Balanced (900 ml) | 3 drops Ca + 3 drops Mg + 3 drops Na | 30 | 7.5 | 37.5 | As above |
Assumptions made for recipe creation:
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One drop = 0.056 g (measured).
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Accepted Lotus / Rao calibration: 1 drop Mg/Ca → +10 ppm GH in 450 ml, 1 drop Na/K → +5 ppm KH in 450 ml.
- Scaling to volume V (ml):
- GH per drop = 10 × (450 / V) [ppm]
- KH per drop = 5 × (450 / V) [ppm]
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For 300 ml: GH/drop = 15 ppm, KH/drop = 7.5 ppm.
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For 900 ml: GH/drop = 5 ppm, KH/drop = 2.5 ppm.
Brief Explanation and Practical Notes
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In the table, most profiles yield GH ≈ 30 ppm and KH = 7.5–15 ppm — this is intentional: we assumed moderate hardness that works well with delicate, light-roasted coffees.
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TDS ≈ GH + KH is a useful approximation for comparisons; do not treat it as an exact conductometer reading.
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Anions (Cl⁻ vs SO₄²⁻) change the experience: chlorides (MgCl₂, CaCl₂) usually give a more "rounded" sweetness and body; sulfates (MgSO₄) can enhance acidity and "snap." Therefore, despite similar GH/KH, profiles may taste different.
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If you want higher GH (more body), increase the number of Mg and/or Ca drops — but do so gradually (1 drop at a time) and test.
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If you have a TDS meter after making the water — measure and compare with the values in the table.
Summary
Water is not just a background, but an equal ingredient in coffee brewing. By controlling minerals, we can make Geisha even more jasmine-like, Kenyan coffee – juicy blackcurrant, and Brazilian coffee – chocolatey and creamy. Thanks to kits like Lotus and Apax or homemade concentrates – baristas and coffee enthusiasts gain a new tool for creating water tailored to the beans.
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