Seattle vs London
Water hardness comparison — how the two cities differ and what it means for your home.
Seattle
united states
21mg/L
Soft Water
1.47°e
Soft
Base Unit (CaCO3): 21 mg/LLocal Unit
HarderFull London data →
London
united kingdom
277mg/L
Very Hard Water
19.39°e
Very Hard
Base Unit (CaCO3): 277 mg/LLocal Unit
Side-by-Side Impact
| Impact Area | Seattle | London |
|---|---|---|
| Limescale buildup | Minimal | Rapid — visible within weeks |
| Boiler/heating risk | Low risk | Annual descaling required |
| Dishwasher salt setting | Low setting (1–2) | Max salt setting (5–7) |
| Skin & hair impact | Low risk | High eczema/dry skin risk |
| Detergent usage | Standard dose | +30–40% more detergent |
Key Findings
Hardness Difference: 256 mg/L
London is significantly harder than Seattle — a difference that has major household implications. Appliances, boiler warranties, and detergent costs will differ substantially.
Moving from Seattle to London?
If you're relocating from Seattle to London, expect visible limescale on taps and shower heads within weeks. You'll need to recalibrate your dishwasher's salt setting, increase kettle descaling frequency, and check your boiler warranty requirements. A shower filter and under-sink scale inhibitor are worth considering immediately.