Coffee Brew Water TDS Target Calculator
Calculate ideal brew water hardness and TDS for coffee.
Compare your tap water TDS against SCA standards and adjust with bottled or filtered water.
Water TDS Status
Brew Water TDS for Coffee
Water makes up 98%+ of coffee — its mineral content (TDS, hardness) directly affects extraction efficiency, sweetness, and clarity.
Specialty Coffee Association (SCA) standards:
| Parameter | Target | Acceptable Range |
|---|---|---|
| Total Dissolved Solids (TDS) | 150 mg/L | 75-250 mg/L |
| Total hardness (CaCO₃) | 68 mg/L | 17-85 mg/L |
| Calcium hardness | 51 mg/L | 17-68 mg/L |
| Total alkalinity | 40 mg/L | 25-80 mg/L |
| pH | 7.0 | 6.5-7.5 |
| Sodium | 10 mg/L | 0-30 mg/L |
| Chlorine | 0 mg/L | 0 mg/L |
Why minerals matter:
- Calcium binds to coffee compounds → extracts flavor better
- Magnesium binds even more strongly → extracts more aromatic compounds
- Bicarbonate / alkalinity buffers acidity → too much mutes brightness
- Sodium is neutral → contributes texture without flavor binding
The “Sweet Spot” rule:
- Around 150 ppm TDS with balanced calcium/magnesium hardness = best extraction for most coffees
- Below 50 ppm: under-extracts — coffee tastes weak and watery
- Above 250 ppm: over-extracts and tastes muddy or bitter
Common water sources:
| Source | Typical TDS | Notes |
|---|---|---|
| Distilled / RO | 0-10 ppm | Too soft — extracts poorly |
| Most tap water | 50-300 ppm | Highly variable; chlorine bad |
| Filtered tap (Brita) | 30-150 ppm | Better, depends on filter age |
| Crystal Geyser | 60-160 ppm | Generally good for coffee |
| Volvic | 100-130 ppm | Good for light roasts |
| Evian | 320 ppm | Too hard for coffee — bitter |
| San Pellegrino | 950 ppm | Way too hard |
| Aquafina | <20 ppm | Too soft |
| “Third Wave Water” mix | ~150 ppm tuned | Designed for coffee |
DIY low-mineral water for coffee:
- Start with distilled or RO water
- Add packaged mineral mixes (Third Wave Water, Lotus) per gallon
- Or DIY: dissolve 1.45g Epsom salt + 0.45g baking soda per gallon distilled
- Provides ~150 ppm hardness, ~75 ppm bicarbonate
Light roast vs dark roast preferences:
- Light roasts: lower bicarbonate (preserves brightness) — 30-50 mg/L
- Dark roasts: higher bicarbonate OK — 60-100 mg/L (smooths out edge)
Espresso machine note: Hard water (above 100 ppm hardness) scales heating elements. Use softened water or descaler regularly. Soft water (below 30 ppm) corrodes copper boilers — there is a sweet spot for machine longevity AND brew quality.