Is South West London a hard water area?
Yes. Tap water across the SW postcode area is very hard, the top band on the scale water companies use, with a median of 258 mg/L calcium carbonate. It ranges from 247 mg/L in SW14 to 318 mg/L in SW4, from 27 districts with their own water company reading.
- Soft
- Moderately soft
- Slightly hard
- Very hard
- Soft
- 0 to 60 mg/L
- Moderately soft
- 60 to 120 mg/L
- Slightly hard
- 120 to 180 mg/L
- Hard
- 180 to 200 mg/L
- Very hard
- 200 to 400 mg/L
Hardness by SW district
Hardest first. Hard starts at 180 mg/L, very hard at 250.
| District | mg/L | Hardness |
|---|---|---|
| SW4 | 318 | very hard |
| SW3 | 313 | very hard |
| SW10 | 281 | very hard |
| SW9 | 273 | very hard |
| SW1H | 268 | very hard |
| SW16 | 268 | very hard |
| SW12 | 263 | very hard |
| SW1V | 262 | very hard |
| SW18 | 262 | very hard |
| SW1Y | 261 | very hard |
| SW13 | 260 | very hard |
| SW8 | 259 | very hard |
| SW11 | 259 | very hard |
| SW1P | 258 | very hard |
| SW17 | 258 | very hard |
| SW2 | 257 | very hard |
| SW6 | 257 | very hard |
| SW20 | 256 | very hard |
| SW1X | 256 | very hard |
| SW1E | 255 | very hard |
| SW19 | 255 | very hard |
| SW1W | 255 | very hard |
| SW15 | 255 | very hard |
| SW5 | 254 | very hard |
| SW7 | 254 | very hard |
| SW1A | 247 | hard |
| SW14 | 247 | hard |
Softener quotes for South West London
At 258 mg/L most SW homes get their money back on a softener within a few years. Free quotes from installers covering your postcode, no obligation.
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Check your exact postcode
The area figure is a median. Your district can sit anywhere between 247 and 318 mg/L.
Nearby areas
- Is South West London a hard water area?
- Yes. The median hardness across SW postcode districts is 258 mg/L calcium carbonate, which is very hard. 100% of the 27 districts we hold readings for are hard or very hard (180 mg/L and above).
- What is the water hardness in South West London?
- Between 247 and 318 mg/L depending on the district, with a median of 258. The hardest measured district is SW4 at 318 mg/L and the softest is SW14 at 247. Figures come from water company drinking-water tests.
- Do I need a water softener in South West London?
- In most SW homes a softener pays for itself: at 258 mg/L kettles, boilers and showers scale up quickly. Check your own district first, because hardness varies from 247 to 318 within the area.
Hardness as mg/L calcium carbonate from water company drinking-water tests and postcode checkers. See the UK hardness map for every area.