Is your water right for coffee?
Coffee is mostly water, and the minerals in it change what ends up in the cup. Enter the numbers from your water report and see how they sit against the Specialty Coffee Association's standard for brewing water.
What do you brew?
Disinfectant on your report
Enter at least your hardness (or TDS) to compare your water with the SCA brewing standard.
The SCA figure is calcium hardness; most water reports give total hardness, which also counts magnesium, so your calcium figure is at or below the number you enter. TDS readings also vary with the meter's conversion factor — the standard uses the 4-4-2 conversion.
The SCA water standard
The figures the checker uses, as the SCA publishes them. The target is the ideal point; landing anywhere in the acceptable range meets the standard. The SCA frames it as the water for a superior extraction of coffee solids, and its own research describes it as the standard for filter preparations.
| Characteristic | Target | Acceptable range |
|---|---|---|
| Calcium hardness | 68 mg/L (4 grains) | 17–85 mg/L (1–5 grains) |
| Total dissolved solids | 150 mg/L | 75–250 mg/L |
| Total alkalinity | 40 mg/L | At or near 40 mg/L |
| pH | 7.0 | 6.5–7.5 |
| Odor | Clean/fresh, odor free | — |
| Color | Clear | — |
| Total chlorine | 0 mg/L | — |
| Sodium | 10 mg/L | At or near 10 mg/L |
What the numbers do
- Alkalinity shapes the taste most.It neutralises the coffee's acids, so high-alkalinity water flattens brightness. The SCA's research piece on water puts its effect on perceived acidity at several hundred times that of pH.
- Hardness matters most to the machine. Across roughly 20–250 mg/L the same piece finds little effect on extraction, but hardness is what forms scale in kettles and boilers.
- Espresso is a different case. The standard was set for filter coffee. Espresso uses far less water per gram of coffee, so alkalinity can run higher before it dulls a shot, while hardness has to stay low to protect the boiler.
Sources
- Specialty Coffee Association of America - Water Standards resource page (Internet Archive copy, July 2023; scaa.org now redirects to sca.coffee)
- Specialty Coffee Association, 25 Magazine Issue 9 - Water and Coffee Acidity: How to Adapt Your Water for Different Extraction Methods (Marco Wellinger, ZHAW)
- Breville - the Oracle BES980 instruction book, Setting Water Hardness (the setting determines how often the DESCALE and CHANGE FILTER alerts appear)
- Third Wave Water - Classic Light Roast Profile product page (add one stick to distilled or RO water; formulated to the SCA water standard)
- Third Wave Water support - What is IN Third Wave Water? (per-profile TDS and alkalinity)
- U.S. Geological Survey - Hardness of Water (soft / moderately hard / hard / very hard bands)
Fix the water
Mineral recipes, filter pitchers and machine-specific cartridges do different jobs. The water guide sorts them by which problem they solve.
Common questions
What is the best water hardness for coffee?
The Specialty Coffee Association's water standard targets a calcium hardness of 68 mg/L (4 grains), with 17 to 85 mg/L (1 to 5 grains) acceptable. It pairs that with about 150 mg/L total dissolved solids and a total alkalinity at or near 40 mg/L.
How do I convert grains per gallon to mg/L?
Multiply by about 17.1. A grain is 64.8 mg and a US gallon is 3.785 litres, so 1 gpg works out to roughly 17.1 mg/L as calcium carbonate. The SCA table rounds this to 17, which is why it lists 4 grains as 68 mg/L. ppm and mg/L are the same thing at drinking-water concentrations.
Is hard water bad for coffee?
For taste, less than people expect. Research published by the SCA links very hard water (above 250 mg/L) with over-extracted flavour and finds little effect on extraction between about 20 and 250 mg/L. The bigger taste lever is alkalinity, which buffers the coffee's acids. Hard water's clearer cost is scale in kettles, brewers and espresso boilers.
Can I brew coffee with distilled water?
Not on its own. The SCA standard puts a floor under hardness and dissolved solids, so empty water sits outside it, and Breville's Oracle manual tells owners never to use distilled or low-mineral water in the machine. Distilled or RO water works as a base once minerals are added back, which is how mineral packets such as Third Wave Water are meant to be used.
Where do I find my water's hardness?
In the United States, your water supplier's annual water quality report (the Consumer Confidence Report) often lists hardness, and sometimes alkalinity and pH; if yours doesn't, the supplier can usually tell you. Hardness test strips, which some espresso machines ship with, and a TDS pen are the quick alternatives.