Water Chemistry
TDS, hardness, and buffer capacity explained for optimal extraction.
Water makes up 98% of your cup of coffee, yet it's often the most overlooked variable in brewing. Understanding water chemistry can unlock flavors you never knew existed in your beans.
Total Dissolved Solids (TDS)
TDS measures all inorganic and organic substances dissolved in water, expressed in parts per million (ppm). The Specialty Coffee Association recommends 75-250 ppm for optimal coffee brewing.
Water that's too pure (low TDS) can actually be aggressive and over-extract coffee, creating harsh flavors. Water with moderate mineral content provides buffering and enhances extraction.
Hardness and Alkalinity
Hardness refers to calcium and magnesium content. These minerals enhance coffee flavor by helping extract desirable compounds.
Alkalinity measures bicarbonate content, which acts as a buffer against coffee's natural acidity. Too much alkalinity creates flat, dull coffee.
The Ideal Water Recipe
Many coffee professionals use a water recipe with approximately 40-70 ppm calcium hardness and 40-75 ppm alkalinity. This balance allows coffee's natural flavors to shine while providing enough buffering to prevent sourness.
You can achieve this by mixing distilled water with minerals like Epsom salt (magnesium sulfate) and baking soda (sodium bicarbonate). Many commercial water solutions are also available for convenience.
Testing Your Water
Simple TDS meters cost less than $20 and provide instant feedback. For comprehensive analysis, water testing kits can measure specific minerals and pH levels, allowing you to optimize your brew water precisely.