Tap Water in CO8
Sudbury and Great Cornard — Anglian Water
Tap water in Sudbury and Great Cornard, supplied by Anglian 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 360 mg/L as CaCO₃. This is notably hard water, among the highest-mineral tap water in England.
Mineral composition
| mg/L | |||
|---|---|---|---|
| Calcium | 132 | ||
| Magnesium | 7 | ||
| Sodium | 22 | ||
| Sulfate | 38 | ||
| Chloride | 37 | ||
| Bicarbonate | ~385 | ||
| ~ Estimated from hardness and ion balance — not directly measured by the water company. | |||
Additional info
| Hardness | 359.545 as CaCO₃ |
| Alkalinity | 315.9 as CaCO₃ |
| pH | 7.37 |
| Conductivity | 671 µS/cm |
| Source | Anglian Water |
| Data year | 2025 |
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
CO8 tap water works well for brewing and baking with little or no adjustment. It has too much mineral content for espresso, aquarium use, tea, and horticulture; a bottled water blend is the better route for those.
Nearby areas
Data sourced from Anglian Water (2025). Looking for a specific address? Look up your full postcode for the most accurate result.