Headstone Water Hardness & Quality Report (2026)
Water Hardness
301+ mg/L
Very Hardestimated · not lab-verified
Source
mixed
pH Level
8.6
neutral = 7.0
Lead
0.001 mg/L
✓ Below action level
TDS
712.8 mg/L
Est. Daily Cost
£0.85
energy & soap waste
Source: DWI Data Portal · Updated 2026
0–99
mg/L
Soft
100–149
mg/L
Slightly Hard
150–199
mg/L
Moderately Hard
200–300
mg/L
Hard
300+
mg/L
Very Hard
Appliance Damage Report
In Headstone, your appliances are currently losing 45% efficiency due to mineral buildup.
| Appliance | In Headstone | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 4.7 yrs | 8.5 yrs | -45% |
| Washing Machine | 6.6 yrs | 12 yrs | -45% |
| Water Heater | 8.3 yrs | 15 yrs | -45% |
Regional Water Comparison
How Headstone compares to its nearest neighbours
| City | Hardness | Clark° | Risk | Source |
|---|---|---|---|---|
| ▶ Headstone, Greater London | ≈ 301+ mg/L | 28.1° | 🔴 Very Hard | mixed |
| Wealdstone, Greater London | ≈ 200–300 mg/L | 17.4° | 🟠 Hard | mixed |
| Harrow, Greater London | ≈ 200–300 mg/L | 15.1° | 🟠 Hard | mixed |
| Harrow Weald, Greater London | ≈ 300+ mg/L | 15° | 🔴 Very Hard | mixed |
| Harrow on the Hill, Greater London | ≈ 300+ mg/L | 15.1° | 🔴 Very Hard | mixed |
National Benchmark
How Headstone compares to the United Kingdom average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Headstone | ≈ 301+ mg/L | 🔴 Very High |
| United Kingdom National Avg | 177 mg/L | 🟡 Moderate |
| Skipton Top Rated | 7.1 mg/L | 🟢 None |
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What Makes Headstone's Water Unique?
Local geology and source profile
Affinity Water supplies Headstone in the London Borough of Harrow, Greater London, UK. Our water primarily comes from groundwater, drawn from the Chalk aquifer through boreholes located in the London Basin. Affinity Water operates treatment facilities, like the Harefield works or other nearby sites, that serve northwest London. This extensive piped network delivers water to Harrow and surrounding boroughs. The watershed for these groundwater sources is the London Basin, where rainfall over chalk downlands replenishes the aquifer. The main geological features are the Cretaceous Chalk Group, a type of limestone aquifer known for its pores and cracks, which naturally infuses the water with calcium and magnesium.
The Chalk Group aquifer, a porous limestone bedrock primarily from the Late Cretaceous period, is the source of Headstone's groundwater. This formation, rich in calcium carbonate, readily dissolves minerals as rainwater filters through it, giving the water its hard quality. The geology of the London Basin, dominated by these calcareous rocks, differs from softer regions with different bedrock, explaining why this supply is mineral-rich and not influenced by surface water.
This characteristically hard water can lead to limescale buildup in appliances like kettles, boilers, washing machines, and showerheads, affecting their efficiency and lifespan. You'll find affected appliances require more frequent descaling; a monthly soak with vinegar or a commercial descaler can help. For households, installing a water softener is a good idea to combat scale, prolong appliance life, and get better lather from soaps and detergents. London's groundwater is monitored and meets UK Drinking Water Inspectorate standards, with a natural pH of about 7.5–8.0. While lead and copper levels are managed through corrosion control, older pipes might add trace amounts. Recent reports show no PFAS exceedances, and treatment includes aeration, filtration, chlorination, and fluoridation at Affinity Water plants.***
Geology & Source: Chalk Group aquifer; porous limestone bedrock rich in calcium carbonate causes hard water
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