Tap Water in DA3
Hartley — South East Water
Tap water in Hartley, supplied by South East Water, has the character of a chalk aquifer source, typical of southern and eastern England. It’s moderately soft, in the lower end of the national range, with a total hardness of 107 mg/L as CaCO₃. Bicarbonate is high at 391 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 | 109 |
| Magnesium | 2 |
| Sodium | 24 |
| Sulfate | 7 |
| Chloride | 20 |
| Bicarbonate | 391 |
Additional info
| Hardness | 107.47 as CaCO₃ |
| Alkalinity | 320.33 as CaCO₃ |
| pH | 7.34 |
| Conductivity | 502.92 µS/cm |
| Source | South East Water |
| Data year | 2025 |
What this means
Kettle & appliances
Some light mineral residue may appear in kettles over time, but significant limescale buildup is unlikely. No treatment needed for most appliances.
Espresso
A good range for espresso. Enough mineral content to provide body and balance acidity without posing a real scale risk to the machine. Most specialty coffee water targets fall in or near this band.
Filter & pour-over
Excellent for filter brewing. The slight mineral content adds body and sweetness without masking acidity, giving a balanced cup across most roast levels. This is close to the SCA’s recommended range for brewed coffee.
Drinking & cooking
Tastes clean with a slight mineral presence. Good all-round water for cooking; it won’t interfere with delicate flavours or leave noticeable deposits.
Bicarbonate
Extremely high buffering that makes this water difficult to work with for any brewing or coffee application without significant dilution or acid treatment: mash pH will sit stubbornly high, extraction will be unbalanced, and espresso will taste flat and chalky with no discernible acidity.
Get the best from your water
DA3 tap water works well for espresso, brewing, baking, and aquarium use with little or no adjustment. It has too much mineral content for tea and horticulture; a bottled water blend is the better route for those.
Nearby areas
Data sourced from South East Water (2025). Looking for a specific address? Look up your full postcode for the most accurate result.