Most people who brew tea think about the tea itself - the origin, the processing, the quality of the leaf. Water is usually an afterthought. But brewing is a chemical process, and in chemistry, there's no room for coincidence.
Water isn't just a vessel for heat. It's an active solvent - the medium through which flavor compounds, tannins, and aromatic molecules are pulled from the leaf and into your cup.
Its mineral composition directly affects how, and how much, of those compounds are extracted. Change the water, and you change the tea.
We wanted to see just how much. So we ran a controlled experiment using three teas at different oxidation levels, a fixed brewing setup, and four water samples with significantly different mineral profiles. The results were clear - and in some cases, surprising.
How We Tested: Setup & Parameters
We used three teas at different oxidation levels. All other brewing parameters were fixed across every sample to isolate water as the single variable.
Tea: 2 g / Water: 150 ml / Temperature: 85°C
Base: distilled water (5 ppm) + added minerals to reach levels of 105–110 ppm
4 Waters, 4 Results: What We Found
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Sample #1 - Third Wave Water (Espresso Profile) pH 5.9 Nice aroma, light and clean, but the body was weak and there were very few tannins. Score: 5/10 |
Sample #2 - Bicarbonate & Mineral Mix F 1.12-1.44 mg/L / HCO₃ 80-100 mg/L / K⁺ 32-38 mg/L / Na⁺ 13-17 mg/L Almost nothing extracted. Flat and empty. Score: 2/10 |
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Sample #3 - Calcium & Magnesium Balance Calcium 75-85 mg/L / Magnesium 17-22 mg/L Rich aroma, full body, long aftertaste, well-balanced tannins. It even helped hide some dryness in the tea. Score: 8/10 |
Sample #4 - Bicarbonate-Heavy Water pH 6.75 Very aromatic, but still under-extracted and lacking depth. Score: 4/10 |
The Best Water for Brewing Tea: Balance Over Purity
From our experiments, one thing became clear: the best water for tea is not about total mineral content, but about balance. The sweet spot we found: a calcium to magnesium ratio of around 3:1, with total mineral content between 30-250 ppm.
Home recommendation: For home use, we recommend magnesium filter cartridges from Aquaphor. In our experience, they work better than most bottled water available in Warsaw supermarkets.
We strongly advise against using reverse osmosis water. But if that's your only option, you can compensate by adjusting your brewing:
- Use +30% more tea
- Lower temperature by 5°C
- Shorten brewing time by ~30 seconds