Tap Water in CM23
Bishop Stortford — Affinity Water
Tap water in Bishop Stortford, supplied by Affinity Water, has the character of a chalk aquifer source, typical of southern and eastern England. It’s hard water, well above the national average, with a total hardness of 345 mg/L as CaCO₃. Bicarbonate is high at 367 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 | 138 |
| Magnesium | 0 |
| Sodium | 13 |
| Sulfate | 30 |
| Chloride | 25 |
| Bicarbonate | 367 |
Additional info
| Hardness | 345 as CaCO₃ |
| Alkalinity | 300.8 as CaCO₃ |
| pH | 7.1 |
| Conductivity | awaiting data |
| Source | Affinity Water |
| Data year | 2024 |
What this means
Kettle & appliances
Limescale is a persistent issue. Kettles fur up quickly, and boilers, dishwashers, and washing machines all accumulate scale that reduces efficiency and shortens lifespan. Water treatment (a softener, inhibitor, or filter) is strongly recommended.
Espresso
Scale is a serious concern at this level: machines need regular descaling and filtration is strongly recommended. In the cup, the water has strong opinions. Light roasts lose their acidity and origin character almost entirely. But dark-roasted, milk-based espresso can work well here. London’s coffee culture developed around exactly this kind of water: strong, dark-roasted coffee served with milk, where the density and body that hard water produces become a virtue rather than a flaw.
Filter & pour-over
Hard water hits filter coffee harder than espresso because the brewing ratio gives it more influence. Lighter roasts will taste flat and indistinct; the buffering neutralises the acidity that carries fruit and floral notes. Darker roasts produce a drinkable but heavy cup. If you’re brewing pour-over with water this hard, the water is the first thing to address.
Drinking & cooking
Noticeably mineral-heavy on the palate. Soap and shampoo lather poorly. Tea may develop a film on the surface (that’s the calcium reacting with tannins). Cooking water may leave a chalky residue on pans.
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
CM23 tap water works well for espresso, brewing, and baking with little or no adjustment. It has too much mineral content for aquarium use, tea, and horticulture; a bottled water blend is the better route for those.
Nearby areas
Data sourced from Affinity Water (2024). Looking for a specific address? Look up your full postcode for the most accurate result.