Best water for coffee brewing.
Coffee is ~98% water. The other 2% takes most of the blame for bad cups, but it's usually the water doing the damage. Here's what actually matters, in numbers and in recipes.
Good brewing water needs roughly 50–175 mg/L total hardness, 40–75 mg/L bicarbonate buffer, and 6.5–7.5 pH. Start with distilled or RO water, add minerals from a recipe. Pavlis, RAO, SCA, BH4, and Melbourne are the five recipes worth knowing.
Why water matters more than you think
Coffee compounds dissolve into water. The water's mineral content determines how they dissolve, how much dissolves, and how the result tastes. Hard water full of scale-forming minerals over-extracts and tastes flat. Soft water under-extracts and tastes sour. Tap water full of chlorine tastes like a swimming pool no matter what coffee you use.
Three numbers control most of it: total hardness (calcium + magnesium), bicarbonate alkalinity (the buffer that resists pH change), and pH (the starting acidity of the water itself).
The three numbers that matter
Total hardness (GH)
The combined concentration of calcium and magnesium, usually expressed in mg/L as CaCO₃. Hardness pulls flavor compounds out of the grounds — too little, and you under-extract; too much, and you over-extract and scale your machine. SCA's recommended range is 50–175 mg/L.
Bicarbonate alkalinity (KH)
Acts as a buffer that resists pH shifts. Low alkalinity makes the cup taste sharp and acidic (acids in the coffee aren't buffered). High alkalinity makes the cup taste flat and chalky (acids get neutralised). SCA target: 40–75 mg/L as CaCO₃.
pH
Starting pH between 6.5 and 7.5 is the safe band. Outside this range, brewing chemistry shifts unpredictably. Most prepared waters land near 7.
The five water recipes worth knowing
1. Pavlis (Hendon & Pavlis)
From Maxwell Colonna-Dashwood, Christopher Hendon, and the Water for Coffee book. Three reservoirs: concentrated calcium, magnesium, and bicarbonate. Mix to taste. Most flexible recipe for tuning per-coffee. Great for experimentation.
2. RAO (Scott Rao)
Scott Rao's preferred profile — relatively low alkalinity, moderate hardness, biased toward magnesium. Reads as a clean, bright cup. Popular for light-roast filter brewing.
3. SCA (Specialty Coffee Association)
The published SCA ideal: 150 mg/L total hardness, ~40 mg/L bicarbonate, ~7 pH. A balanced middle-of-the-road target that's safe across roast levels and brew methods. Good default.
4. BH4 (Barista Hustle & Lance Hedrick)
A recipe that's gained traction in competition circles. Higher magnesium, lower calcium, moderate buffer. Tends to amplify clarity and sweetness without sacrificing body.
5. Melbourne (third-wave Australian)
A regional profile that became influential through Melbourne's specialty scene — softer than SCA, with low alkalinity and moderate hardness. Reads as a clean, sweet, transparent cup.
| Recipe | Profile | Best for |
|---|---|---|
| Pavlis | Tunable — three concentrates | Experimentation |
| RAO | Low alkalinity, magnesium-biased | Light roasts, filter |
| SCA | Balanced, mid-range hardness | Safe default, any roast |
| BH4 | High magnesium, moderate buffer | Clarity, sweetness |
| Melbourne | Soft, low alkalinity | Clean, transparent cups |
How to actually mix it
- Start with a clean base. Distilled or reverse-osmosis water. Both strip out everything; you add back what you want.
- Use food-grade salts. Epsom salt (magnesium sulfate), calcium chloride or citrate, sodium bicarbonate. Lotus salts and TWW (Third Wave Water) sachets are pre-portioned alternatives.
- Mix concentrates, then dilute. Recipes typically have you mix small concentrate bottles, then add measured amounts of each into a litre of distilled water.
- Use it the same day. Mineral solutions don't store well; bicarbonate degrades.
- Stick with one recipe for a week. Don't change recipes between brews — you won't know whether the recipe or the coffee changed.
The shortcut: pre-portioned packets
If mixing salts feels like running a chemistry lab, two products simplify it:
- Third Wave Water (TWW). Sachets you drop into a gallon of distilled water. Easy, reasonably tuned, no math.
- Lotus Coffee Water. Concentrates and mineral salts marketed specifically at home baristas. Comparable convenience.
Both are excellent upgrades over tap, even if they don't quite match a custom Pavlis or BH4 recipe.
What about espresso machines?
Important caveat: high-calcium recipes can scale boilers and clog group heads. If you're feeding a prosumer espresso machine, use lower-hardness recipes (Melbourne, RAO) and watch for scale. Distilled water alone in an espresso machine is also problematic — pure water corrodes seals and triggers low-water sensors. Aim for the lower end of the SCA range (around 50–80 mg/L hardness) for machine longevity.
Tracking water alongside brews
Water profile is one of the parameters HomeBarista logs per brew. Once you find a recipe that makes a coffee sing, the water profile is part of the saved reference — so the next bag, the next morning, you're not just remembering the grind and dose but the water too.
The built-in water recipe calculator has all five presets above, with step-by-step instructions and final mineral concentrations displayed.
5 water presets + step-by-step mixing in HomeBarista.
Pavlis, RAO, SCA, BH4, Melbourne — calculated and saved per brew. Free on iOS.
