The Best Water for Coffee by James Hoffmann
I. Water Chemistry and Coffee
Two aspects of water content are crucial for brewing coffee:
| Component | Function in Coffee Extraction | Taste Impact of Imbalance |
|---|---|---|
| Mineral Ions (Calcium and Magnesium) | Aid Extraction. These ions help dissolve flavor compounds from the coffee grounds into the water. | Too Little: Very little extraction. Too Much: Not necessarily better. |
| Bicarbonate / Alkalinity (Buffer) | Buffer Acidity. It neutralises the natural acids extracted from the coffee, helping to balance the pH. | Too Little: Acids run rampant, resulting in uncontrolled, unbalanced, and unpleasant acidity. Too Much: Everything tastes dull, boring, and brown . |
II. Water Quality Guidelines
While there is no single perfect water recipe, the speaker offers general ranges, noting that matching a roaster's water profile can help achieve their tasting notes.
| Component | Recommended Range | Notes |
|---|---|---|
| Calcium | 30 to 50 parts per million (ppm) | A little more calcium is generally preferable. |
| Magnesium | 15 to 30 parts per million (ppm) | A little less magnesium is preferable. |
| Bicarbonate / Buffer | 50 to 75 parts per million (ppm) |
III. Assessing and Treating Water
Assessing Your Water
- Water Authority: Check your local water authority's website (often by zip/post code) for an exhaustive breakdown of mineral content.
- Dropper Kit: This is a cheaper way to assess total hardness and carbonate hardness, which can be converted into useful data (more accurate than a TDS meter).
Treatment Options
- Pitcher Filters (e.g., Brita):
- Action: They use active carbon to clean up off-tastes like chlorine and contain ion exchange beads to swap calcium for sodium.
- Effectiveness: They improve taste but are not a perfect solution for softening very hard water. They are finite and not very effective with very hard water.
- Note: Hard water leads to limescale, which damages and clogs coffee equipment.
- Bottled Water:
- Pros: Labels provide the exact mineral, calcium, magnesium, and bicarbonate content, allowing you to select a water with a known profile.
- Cons: The speaker considers this an "inelegant, frustrating, wasteful, [and] environmentally unsound" solution.
- Reverse Osmosis (RO):
- Action: Pressure is used to force water through a fine mesh, separating pure water from minerals (which run off as waste).
- Effectiveness: RO units are often too effective, producing nearly pure water that is corrosive and lacks the necessary minerals for good extraction.
- Custom Mineral Water (The Extreme Solution):
- Action: This involves buying pure demineralised water and adding specific minerals to create a perfect recipe.
- Method: Use commercial sachets (like Third Wave Water) or create your own solution using Epsom salt (magnesium) and sodium bicarbonate/baking soda (bicarbonate).
- Resources: The speaker gives a strong recommendation to Barista Hustle for their free information, calculators, and water recipes.
The speaker encourages everyone to experiment by brewing two cups of coffee (e.g., in a French press): one with soft water and one with hard water, as the difference in taste is "enormous" and perceptible by anyone.