Tap Water in BN21
Mill Gap 2 — South East Water
Tap water in Mill Gap 2, supplied by South East Water, has the character of a chalk aquifer source, typical of southern and eastern England. It's soft water, low in dissolved minerals, with a total hardness of 80 mg/L as CaCO₃. Bicarbonate is high at 283 mg/L: this water suits dark-roasted, milk-based coffee well, but will strip the acidity from lighter roasts and pour-over brewing.
Mineral composition
| mg/L | |
|---|---|
| Calcium | 85 |
| Magnesium | 3 |
| Sodium | 19 |
| Sulfate | 23 |
| Chloride | 44 |
| Bicarbonate | 283 |
Additional info
| Hardness | 79.85 as CaCO₃ |
| Alkalinity | 232.25 as CaCO₃ |
| pH | 7.68 |
| Conductivity | 531 µS/cm |
| Source | South East Water |
| Data year | 2025 |
What this means
Kettle & appliances
At this level of hardness, limescale is essentially a non-issue. Kettles, boilers, and heating elements will stay clean without treatment.
Espresso
Soft water is forgiving on espresso machines (no scale risk) but can produce a thinner, more acidic shot. The low mineral content means less buffering, so bright and sour notes tend to dominate. That said, lighter roasts can shine here in ways they won't in harder water.
Filter & pour-over
This is where soft water shows its range. A V60 or Chemex will produce a bright, clean, highly readable cup with clear origin character. Light and medium roasts tend to be at their most expressive. It can tip into sourness with very light roasts, but for most specialty filter coffee, this water is close to ideal.
Drinking & cooking
This water tastes clean and neutral. It lathers easily, rinses cleanly, and won't leave mineral deposits on glassware or cookware.
Bicarbonate
Heavily buffered water that resists pH change substantially: suited only to the darkest, most roast-forward beer styles (and even then may need dilution), while espresso at this level will taste dull, chalky, and lacking definition, with almost all origin character neutralised by the alkalinity.
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Data sourced from South East Water (2025). Looking for a specific address? Look up your full postcode for the most accurate result.