BrewWater
What TDS should coffee brewing water be?
Short answer
One hundred and fifty milligrams per litre is the published target, with seventy-five to two hundred and fifty treated as acceptable. Falling anywhere inside that range meets the standard. Meters report differently depending on their conversion factor, so the same water can read as two different numbers.
| 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 sodium concentration for brewing water | 10 | mg/L | Specialty Coffee Association of America · verified |
Target versus acceptable range
The standard is explicit that the target is the most desirable point within the acceptable range, and that water falling anywhere inside the range still meets the standard. The range exists to accommodate real world circumstances rather than to mark a pass or fail line at the target itself.
Why your meter may disagree
Handheld meters measure conductivity and convert it to an estimated dissolved solids figure. The standard footnotes that its numbers assume a 4-4-2 conversion. A meter using a different factor reports a different value for identical water, so comparing readings between meters is not meaningful without knowing both factors.
Hitting the TDS target is not sufficient on its own
Total dissolved solids counts everything in solution, so water can sit at exactly one hundred and fifty while being wrong in composition — high sodium, low hardness, low alkalinity. The TDS figure is a useful sanity check rather than a complete specification.