BrewWater
What water quality does the SCA recommend for brewing coffee?
Short answer
The 2009 SCAA standard targets 150 mg/L total dissolved solids, accepting 75 to 250. It asks for 40 mg/L total alkalinity, 68 mg/L calcium hardness, pH 7.0 within a 6.5 to 7.5 band, sodium near 10 mg/L, and zero total chlorine.
| Measure | Value | Unit | Source |
|---|---|---|---|
| Target total dissolved solids for brewing water | 150 | mg/L | Specialty Coffee Association of America · verified |
| Acceptable total dissolved solids range for brewing water | 75–250 | mg/L | Specialty Coffee Association of America · verified |
| Target total alkalinity for brewing water | 40 | mg/L as CaCO3 | Specialty Coffee Association of America · verified |
| Target calcium hardness for brewing water | 68 | mg/L as CaCO3 | Specialty Coffee Association of America · verified |
| Acceptable calcium hardness range for brewing water | 17–85 | mg/L as CaCO3 | Specialty Coffee Association of America · verified |
| Target pH for brewing water | 7 | pH | Specialty Coffee Association of America · verified |
| Acceptable pH range for brewing water | 6.5–7.5 | pH | Specialty Coffee Association of America · verified |
| Target sodium concentration for brewing water | 10 | mg/L | Specialty Coffee Association of America · verified |
| Total chlorine permitted in brewing water | 0 | mg/L | Specialty Coffee Association of America · verified |
What are the exact target values?
The table on this page reproduces every numeric row of the standard with its source. Two rows are not numeric and so do not appear there: the standard also asks for water that is clean, fresh and odour free, and clear in colour, both judged by sensory assessment rather than measurement.
Why does the standard separate targets from acceptable ranges?
The document is explicit about this. The target is described as the most desirable point within the acceptable range, and water falling anywhere inside the range is still considered to meet the standard. The ranges exist to accommodate real world circumstances. Three rows have no numeric range at all: alkalinity and sodium are given as at or near their targets, and total chlorine is a single value of zero.
Why does the standard limit sodium?
Sodium is capped near 10 mg/L, which is low enough to rule out most softened water. Ion-exchange softening works by replacing calcium and magnesium with sodium, so water that has been through a domestic softener will usually sit well above this figure even though its hardness now looks ideal.
How old is this standard, and does it still apply?
The document is version 21NOV2009A, revised in November 2009 and published by the Specialty Coffee Association of America, which merged with its European counterpart to form the SCA in 2017. It is still the figure set the industry quotes. Worth knowing when you see it cited as current: it is a 2009 document, and this page says so rather than implying otherwise.
Common questions
- Is TDS the same as hardness?
- No. Total dissolved solids counts everything dissolved in the water, while hardness counts only the polyvalent cations, mostly calcium and magnesium. Water can meet the TDS target and still be far outside the hardness range.
- What does the 4-4-2 conversion footnote mean?
- The standard footnotes that its TDS figures assume a 4-4-2 conversion, which is the factor a meter uses to turn a conductivity reading into a dissolved solids number. Meters using a different factor will report a different value for the same water.