Water for coffee: minerals, TDS, and perfect extraction

May 1, 2026Carrera Café
Technical guide

Water for coffee

Minerals, TDS, and perfect extraction

Coffee is 98% water. What you put in the kettle conditions the result almost as much as the bean itself. Understanding water is the final step toward the perfect cup.

The basics

Why water is so important

Coffee's solvent

Water is not just a carrier: it is an active solvent. Its dissolved minerals interact with the aromatic compounds of coffee during extraction. Too few minerals, and the water extracts incompletely, leaving the coffee flat and underdeveloped. Too many minerals, and it dominates the aromas, making the cup harsh and metallic.

The Specialty Coffee Association has established ideal parameters for brewing water. These recommendations are not arbitrary: they result from hundreds of comparative extraction tests. Good water is a setting like any other in the recipe.

Key parameters

TDS, hardness, and pH

What you need to measure

TDS (Total Dissolved Solids)
★ Priority 1

The measurement of dissolved solids indicates the total amount of minerals present in the water. It is measured in ppm (parts per million).

Too low
< 75 ppm
Ideal SCA
75–150 ppm
Too high
> 250 ppm
Hardness and Magnesium

Magnesium is the mineral most favorable for coffee extraction. It has a particular affinity for aromatic compounds. Calcium stabilizes extraction but contributes to machine scaling.

Ideal Magnesium
10–30 mg/L
Ideal Calcium
40–75 mg/L
Water pH

Water that is too acidic or too alkaline disrupts the aromatic balance. Coffee itself contains organic acids: neutral water allows these acids to express themselves freely.

Ideal zone
pH 6.5 – 7.5
To avoid
< 6 or > 8
Practical guide

Which water to use at home

Concrete solutions for every situation

Tap water (Québec)

Montreal water is generally soft and of good quality. TDS often between 100 and 180 ppm. Acceptable for drip coffee, may require a charcoal filter to remove chlorine.

Filtered water (Brita, under-sink filter)

Removes chlorine and some contaminants. Significantly improves taste. Warning: some reverse osmosis filters remove too many minerals (TDS too low). Consider remineralizing.

Bottled water

Practical solution. Choose slightly mineralized waters (Volvic, light Evian). Avoid highly mineralized waters like Hépar or San Pellegrino that disrupt extraction.

Remineralized water (expert level)

For enthusiasts: start with distilled water and add magnesium and bicarbonate concentrates according to precise ratios. Total control of the mineral profile. The Third Wave Water formula is popular in the community.

Temperature

Heat, the final parameter

Neither too hot nor too cold

Extraction temperature is an accelerator or brake on the solubility of coffee compounds. Too hot, you extract too fast and burn delicate aromas. Too cold, you under-extract and the coffee remains bitter and hollow.

Espresso
90–94°C
Filter (light)
92–96°C
Filter (dark)
88–92°C
Barista equipment

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Gooseneck kettles, filters, precision accessories — everything to control every parameter of your extraction.

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