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☕ SourShot
espresso water chemistry · SCA target · scale predictor
Typical range: 30–400 ppm
Default city average: pH 7.6 (typical US/EU)
🎛️ Brewer's choice mode
📊 Dosing & Prediction
🍋 Citric acid (5% sol): — drops
adjusted to your brew volume
adjusted to your brew volume
🧂 Baking soda (sat'd): — drops
only if alkalinity too low
only if alkalinity too low
🧴 Brewer's choice addition: — (disabled)
🔮 Kettle scaling predictor: — brews until descaling
temperature-compensated model based on LSI & brew temp
temperature-compensated model based on LSI & brew temp
⚠️ Drops based on standard dropper (~0.05mL). Use 5% citric acid solution (50g/L).
ultimate grind guide
french press vs pour-over
light vs dark roast
french press recipe
pour-over guide
SourShot: Master Your Espresso Water Chemistry
📘 How to Use the Calculator
Using SourShot is simple. Start by entering your tap water's total hardness (ppm CaCO₃) and pH — grab these from a local water report or $10 test strips. For best accuracy, optionally add calcium and magnesium levels, plus a TDS reading if you have a meter. Next, select your brew volume (from 0.5L to 5 gallons) and brew temperature (espresso vs. pour-over). The tool automatically scales chemical doses to your batch size. Click "Calculate & Adjust" — SourShot instantly tells you exactly how many drops of 5% citric acid (to lower alkalinity) or baking soda solution (to raise it) to add per batch to hit the Specialty Coffee Association (SCA) standard of 50 mg/L alkalinity. Enable "Brewer's Choice" mode to boost magnesium for chocolatey body or reduce buffer for bright, acidic shots. The built-in kettle scaling predictor estimates how many brews until descaling, now temperature-compensated for accuracy.
🔥 Why It Matters
Third-wave water packets cost $0.50–$1.00 per gallon and create plastic waste. Tap water varies wildly — too much alkalinity dulls acidity; too little makes shots sour or hollow. SourShot turns any tap water into SCA-compliant brew water for pennies, while preventing costly scale damage to your espresso machine. With the scaling predictor you can plan descaling, avoid heating element failure, and keep your shots consistent. Water chemistry is the invisible ingredient that separates good espresso from transcendent espresso.
🧪 The Math Behind It
The calculator estimates current alkalinity from hardness and pH. For example, water with 180 ppm hardness and pH 7.9 has ~135 ppm alkalinity. To reach the SCA target of 50 ppm, you need to neutralize 85 ppm as CaCO₃. Each drop of 5% citric acid neutralizes ~2.5 mg CaCO₃ equivalent per gallon. Formula:
Drops = (Current_Alkalinity - 50) × 0.47 × 3.785 ÷ 2.5 × Volume_Gallons
The scaling predictor uses the Langelier Saturation Index (LSI) adjusted for brew temperature — hotter water scales faster. For instance, raising brew temp from 93°C to 100°C can reduce descaling interval by ~30%. Magnesium boost calculations use MgSO₄ stoichiometry: 0.15g Epsom salt per gallon adds ~12 ppm Mg²⁺, enhancing sweetness and body.
❓ Common Questions
- Do I need a pH meter? Helpful but not required. Use city averages or test strips (accuracy ±0.5 pH is fine).
- Can I use this for pour-over? Yes — just select the correct brew temperature and volume. The chemistry works for any coffee brewing.
- Is citric acid safe for espresso machines? Yes, in small amounts. It descales safely and rinses clean. Never use vinegar.
- What if my water is already perfect? The calculator will tell you — no drops needed! Just enjoy your brew.
- How often should I descale? Follow the scaling predictor; it's tailored to your water, temp, and brew frequency.
- Can I save my water profile? Currently manual entry, but use the city library as a starting point and adjust.
SourShot is free, open-source friendly, and built for coffee lovers who refuse to leave water chemistry to chance.
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