WaterThames Water Water Hardness
London & Thames Valley • 354 postcodes served
Very Hard
302
Average ppm
250
Minimum ppm
350
Maximum ppm
354
Postcodes Served
About Thames Water
Thames Water is the largest water and wastewater services company in the UK, serving over 15 million customers across London and the Thames Valley. The region sits on chalk and limestone aquifers, producing notoriously hard water with high calcium carbonate levels.
Hardness Distribution
0
Soft (0%)
0
Slightly Hard (0%)
0
Moderate (0%)
163
Hard (46%)
191
Very Hard (54%)
All Areas Served by Thames Water
| Postcode | Town | Hardness | PPM | Level |
|---|---|---|---|---|
| E7 | London | 350 ppm | Very Hard | |
| OX13 | Abingdon | 350 ppm | Very Hard | |
| SL3 | Slough | 350 ppm | Very Hard | |
| E6 | London | 349 ppm | Very Hard | |
| OX12 | Wantage | 349 ppm | Very Hard | |
| OX44 | Oxford | 349 ppm | Very Hard | |
| SL2 | Slough | 349 ppm | Very Hard | |
| E5 | London | 348 ppm | Very Hard | |
| OX11 | Didcot | 348 ppm | Very Hard | |
| SL1 | Slough | 348 ppm | Very Hard | |
| E4 | London | 347 ppm | Very Hard | |
| OX10 | Wallingford | 347 ppm | Very Hard | |
| SL0 | Iver | 347 ppm | Very Hard | |
| E3 | London | 346 ppm | Very Hard | |
| KT24 | Leatherhead | 346 ppm | Very Hard | |
| N9 | London | 346 ppm | Very Hard | |
| E2 | London | 345 ppm | Very Hard | |
| KT23 | Leatherhead | 345 ppm | Very Hard | |
| N8 | London | 345 ppm | Very Hard | |
| E1 | London | 344 ppm | Very Hard | |
| KT22 | Leatherhead | 344 ppm | Very Hard | |
| N7 | London | 344 ppm | Very Hard | |
| KT21 | Ashtead | 343 ppm | Very Hard | |
| N6 | London | 343 ppm | Very Hard | |
| KT20 | Tadworth | 342 ppm | Very Hard | |
| N5 | London | 342 ppm | Very Hard | |
| N4 | London | 341 ppm | Very Hard | |
| N3 | London | 340 ppm | Very Hard | |
| W9 | London | 340 ppm | Very Hard | |
| N2 | London | 339 ppm | Very Hard | |
| RM19 | Purfleet On Thames | 339 ppm | Very Hard | |
| W8 | London | 339 ppm | Very Hard | |
| N1 | London | 338 ppm | Very Hard | |
| RM18 | Tilbury | 338 ppm | Very Hard | |
| W7 | London | 338 ppm | Very Hard | |
| RM17 | Grays | 337 ppm | Very Hard | |
| W6 | London | 337 ppm | Very Hard | |
| HA9 | Wembley | 336 ppm | Very Hard | |
| RM16 | Grays | 336 ppm | Very Hard | |
| W5 | London | 336 ppm | Very Hard | |
| HA8 | Edgware | 335 ppm | Very Hard | |
| OX9 | Thame | 335 ppm | Very Hard | |
| RM15 | South Ockendon | 335 ppm | Very Hard | |
| W4 | London | 335 ppm | Very Hard | |
| HA7 | Stanmore | 334 ppm | Very Hard | |
| RM14 | Upminster | 334 ppm | Very Hard | |
| W3 | London | 334 ppm | Very Hard | |
| GU35 | Bordon | 333 ppm | Very Hard | |
| HA6 | Northwood | 333 ppm | Very Hard | |
| OX7 | Chipping Norton | 333 ppm | Very Hard | |
| RM13 | Rainham | 333 ppm | Very Hard | |
| W2 | London | 333 ppm | Very Hard | |
| GU34 | Alton | 332 ppm | Very Hard | |
| HA5 | Pinner | 332 ppm | Very Hard | |
| RM12 | Hornchurch | 332 ppm | Very Hard | |
| GU33 | Liss | 331 ppm | Very Hard | |
| HA4 | Ruislip | 331 ppm | Very Hard | |
| IG11 | Barking | 331 ppm | Very Hard | |
| OX5 | Kidlington | 331 ppm | Very Hard | |
| RM11 | Hornchurch | 331 ppm | Very Hard | |
| GU32 | Petersfield | 330 ppm | Very Hard | |
| HA3 | Harrow | 330 ppm | Very Hard | |
| IG10 | Loughton | 330 ppm | Very Hard | |
| OX4 | Oxford | 330 ppm | Very Hard | |
| RM10 | Dagenham | 330 ppm | Very Hard | |
| GU31 | Petersfield | 329 ppm | Very Hard | |
| HA2 | Harrow | 329 ppm | Very Hard | |
| OX3 | Oxford | 329 ppm | Very Hard | |
| GU30 | Liphook | 328 ppm | Very Hard | |
| HA1 | Harrow | 328 ppm | Very Hard | |
| OX2 | Oxford | 328 ppm | Very Hard | |
| HA0 | Wembley | 327 ppm | Very Hard | |
| OX1 | Oxford | 327 ppm | Very Hard | |
| RG31 | Reading | 327 ppm | Very Hard | |
| SE9 | London | 327 ppm | Very Hard | |
| HP9 | Beaconsfield | 326 ppm | Very Hard | |
| RG30 | Reading | 326 ppm | Very Hard | |
| SE28 | London | 326 ppm | Very Hard | |
| SE8 | London | 326 ppm | Very Hard | |
| SW20 | London | 326 ppm | Very Hard | |
| HP8 | Chalfont St Giles | 325 ppm | Very Hard | |
| SE27 | London | 325 ppm | Very Hard | |
| SE7 | London | 325 ppm | Very Hard | |
| HP7 | Amersham | 324 ppm | Very Hard | |
| NW9 | London | 324 ppm | Very Hard | |
| SE26 | London | 324 ppm | Very Hard | |
| SE6 | London | 324 ppm | Very Hard | |
| DA9 | Greenhithe | 323 ppm | Very Hard | |
| HP6 | Amersham | 323 ppm | Very Hard | |
| NW8 | London | 323 ppm | Very Hard | |
| SE25 | London | 323 ppm | Very Hard | |
| SE5 | London | 323 ppm | Very Hard | |
| DA8 | Erith | 322 ppm | Very Hard | |
| HP5 | Chesham | 322 ppm | Very Hard | |
| NW7 | London | 322 ppm | Very Hard | |
| SE24 | London | 322 ppm | Very Hard | |
| SE4 | London | 322 ppm | Very Hard | |
| DA7 | Bexleyheath | 321 ppm | Very Hard | |
| HP4 | Berkhamsted | 321 ppm | Very Hard | |
| NW6 | London | 321 ppm | Very Hard | |
| OX39 | Chinnor | 321 ppm | Very Hard | |
| SE23 | London | 321 ppm | Very Hard | |
| SE3 | London | 321 ppm | Very Hard | |
| DA6 | Bexleyheath | 320 ppm | Very Hard | |
| HP3 | Hemel Hempstead | 320 ppm | Very Hard | |
| NW5 | London | 320 ppm | Very Hard | |
| SE2 | London | 320 ppm | Very Hard | |
| SE22 | London | 320 ppm | Very Hard | |
| DA5 | Bexley | 319 ppm | Very Hard | |
| HP2 | Hemel Hempstead | 319 ppm | Very Hard | |
| NW4 | London | 319 ppm | Very Hard | |
| SE1 | London | 319 ppm | Very Hard | |
| SE21 | London | 319 ppm | Very Hard | |
| DA4 | Dartford | 318 ppm | Very Hard | |
| HP1 | Hemel Hempstead | 318 ppm | Very Hard | |
| KT19 | Epsom | 318 ppm | Very Hard | |
| NW3 | London | 318 ppm | Very Hard | |
| SE20 | London | 318 ppm | Very Hard | |
| DA3 | Longfield | 317 ppm | Very Hard | |
| KT18 | Epsom | 317 ppm | Very Hard | |
| NW2 | London | 317 ppm | Very Hard | |
| DA2 | Dartford | 316 ppm | Very Hard | |
| KT17 | Epsom | 316 ppm | Very Hard | |
| NW1 | London | 316 ppm | Very Hard | |
| DA1 | Dartford | 315 ppm | Very Hard | |
| KT16 | Chertsey | 315 ppm | Very Hard | |
| OX33 | Oxford | 315 ppm | Very Hard | |
| SW9 | London | 315 ppm | Very Hard | |
| KT15 | Addlestone | 314 ppm | Very Hard | |
| RG9 | Henley On Thames | 314 ppm | Very Hard | |
| SW8 | London | 314 ppm | Very Hard | |
| UB11 | Uxbridge | 314 ppm | Very Hard | |
| KT14 | West Byfleet | 313 ppm | Very Hard | |
| RG8 | Reading | 313 ppm | Very Hard | |
| SW7 | London | 313 ppm | Very Hard | |
| UB10 | Uxbridge | 313 ppm | Very Hard | |
| KT13 | Weybridge | 312 ppm | Very Hard | |
| RG7 | Reading | 312 ppm | Very Hard | |
| SW6 | London | 312 ppm | Very Hard | |
| GU9 | Farnham | 311 ppm | Very Hard | |
| KT12 | Walton On Thames | 311 ppm | Very Hard | |
| RG6 | Reading | 311 ppm | Very Hard | |
| SW5 | London | 311 ppm | Very Hard | |
| GU8 | Godalming | 310 ppm | Very Hard | |
| IG9 | Buckhurst Hill | 310 ppm | Very Hard | |
| KT11 | Cobham | 310 ppm | Very Hard | |
| RG5 | Reading | 310 ppm | Very Hard | |
| RM9 | Dagenham | 310 ppm | Very Hard | |
| SW4 | London | 310 ppm | Very Hard | |
| GU7 | Godalming | 309 ppm | Very Hard | |
| IG8 | Woodford Green | 309 ppm | Very Hard | |
| KT10 | Esher | 309 ppm | Very Hard | |
| RG4 | Reading | 309 ppm | Very Hard | |
| RM8 | Dagenham | 309 ppm | Very Hard | |
| SW3 | London | 309 ppm | Very Hard | |
| GU6 | Cranleigh | 308 ppm | Very Hard | |
| IG7 | Chigwell | 308 ppm | Very Hard | |
| N22 | London | 308 ppm | Very Hard | |
| RM7 | Romford | 308 ppm | Very Hard | |
| SW2 | London | 308 ppm | Very Hard | |
| GU5 | Guildford | 307 ppm | Very Hard | |
| IG6 | Ilford | 307 ppm | Very Hard | |
| N21 | London | 307 ppm | Very Hard | |
| RG2 | Reading | 307 ppm | Very Hard | |
| RM6 | Romford | 307 ppm | Very Hard | |
| TW20 | Egham | 307 ppm | Very Hard | |
| GU4 | Guildford | 306 ppm | Very Hard | |
| IG5 | Ilford | 306 ppm | Very Hard | |
| N20 | London | 306 ppm | Very Hard | |
| RG1 | Reading | 306 ppm | Very Hard | |
| RM5 | Romford | 306 ppm | Very Hard | |
| GU3 | Guildford | 305 ppm | Very Hard | |
| IG4 | Ilford | 305 ppm | Very Hard | |
| RM4 | Romford | 305 ppm | Very Hard | |
| GU2 | Guildford | 304 ppm | Very Hard | |
| GU29 | Midhurst | 304 ppm | Very Hard | |
| IG3 | Ilford | 304 ppm | Very Hard | |
| RM3 | Romford | 304 ppm | Very Hard | |
| GU1 | Guildford | 303 ppm | Very Hard | |
| GU28 | Petworth | 303 ppm | Very Hard | |
| IG2 | Ilford | 303 ppm | Very Hard | |
| RM2 | Romford | 303 ppm | Very Hard | |
| E20 | Olympic Park | 302 ppm | Very Hard | |
| GU27 | Haslemere | 302 ppm | Very Hard | |
| IG1 | Ilford | 302 ppm | Very Hard | |
| RG29 | Hook | 302 ppm | Very Hard | |
| RM1 | Romford | 302 ppm | Very Hard | |
| SW19 | London | 302 ppm | Very Hard | |
| GU26 | Hindhead | 301 ppm | Very Hard | |
| RG28 | Whitchurch | 301 ppm | Very Hard | |
| SW18 | London | 301 ppm | Very Hard | |
| GU25 | Virginia Water | 300 ppm | Hard | |
| RG27 | Hook | 300 ppm | Hard | |
| SW17 | London | 300 ppm | Hard | |
| GU24 | Woking | 299 ppm | Hard | |
| RG26 | Tadley | 299 ppm | Hard | |
| SW16 | London | 299 ppm | Hard | |
| GU23 | Woking | 298 ppm | Hard | |
| RG25 | Basingstoke | 298 ppm | Hard | |
| SW15 | London | 298 ppm | Hard | |
| GU22 | Woking | 297 ppm | Hard | |
| RG24 | Basingstoke | 297 ppm | Hard | |
| SW14 | London | 297 ppm | Hard | |
| GU21 | Woking | 296 ppm | Hard | |
| RG23 | Basingstoke | 296 ppm | Hard | |
| SW13 | London | 296 ppm | Hard | |
| W1C | London | 296 ppm | Hard | |
| GU20 | Windlesham | 295 ppm | Hard | |
| GU52 | Fleet | 295 ppm | Hard | |
| RG22 | Basingstoke | 295 ppm | Hard | |
| SW12 | London | 295 ppm | Hard | |
| GU51 | Fleet | 294 ppm | Hard | |
| RG21 | Basingstoke | 294 ppm | Hard | |
| SE19 | London | 294 ppm | Hard | |
| SW11 | London | 294 ppm | Hard | |
| RG20 | Newbury | 293 ppm | Hard | |
| SE18 | London | 293 ppm | Hard | |
| SW10 | London | 293 ppm | Hard | |
| TW9 | Richmond | 293 ppm | Hard | |
| HP27 | Princes Risborough | 292 ppm | Hard | |
| SE17 | London | 292 ppm | Hard | |
| TW8 | Brentford | 292 ppm | Hard | |
| KT9 | Chessington | 291 ppm | Hard | |
| SE16 | London | 291 ppm | Hard | |
| TW7 | Isleworth | 291 ppm | Hard | |
| KT8 | West Molesey | 290 ppm | Hard | |
| SE15 | London | 290 ppm | Hard | |
| KT7 | Thames Ditton | 289 ppm | Hard | |
| SE14 | London | 289 ppm | Hard | |
| TW5 | Hounslow | 289 ppm | Hard | |
| HP23 | Tring | 288 ppm | Hard | |
| KT6 | Surbiton | 288 ppm | Hard | |
| NW11 | London | 288 ppm | Hard | |
| OX29 | Witney | 288 ppm | Hard | |
| SE13 | London | 288 ppm | Hard | |
| TW4 | Hounslow | 288 ppm | Hard | |
| HP22 | Aylesbury | 287 ppm | Hard | |
| KT5 | Surbiton | 287 ppm | Hard | |
| NW10 | London | 287 ppm | Hard | |
| OX28 | Witney | 287 ppm | Hard | |
| SE12 | London | 287 ppm | Hard | |
| TW3 | Hounslow | 287 ppm | Hard | |
| HP21 | Aylesbury | 286 ppm | Hard | |
| KT4 | Worcester Park | 286 ppm | Hard | |
| OX27 | Bicester | 286 ppm | Hard | |
| SE11 | London | 286 ppm | Hard | |
| TW2 | Twickenham | 286 ppm | Hard | |
| HP20 | Aylesbury | 285 ppm | Hard | |
| KT3 | New Malden | 285 ppm | Hard | |
| OX26 | Bicester | 285 ppm | Hard | |
| SE10 | London | 285 ppm | Hard | |
| TW1 | Twickenham | 285 ppm | Hard | |
| UB9 | Uxbridge | 285 ppm | Hard | |
| KT2 | Kingston Upon Thames | 284 ppm | Hard | |
| OX25 | Bicester | 284 ppm | Hard | |
| UB8 | Uxbridge | 284 ppm | Hard | |
| KT1 | Kingston Upon Thames | 283 ppm | Hard | |
| TW19 | Staines Upon Thames | 283 ppm | Hard | |
| UB7 | West Drayton | 283 ppm | Hard | |
| N19 | London | 282 ppm | Hard | |
| TW18 | Staines Upon Thames | 282 ppm | Hard | |
| UB6 | Greenford | 282 ppm | Hard | |
| N18 | London | 281 ppm | Hard | |
| TW17 | Shepperton | 281 ppm | Hard | |
| UB5 | Northolt | 281 ppm | Hard | |
| W14 | London | 281 ppm | Hard | |
| N17 | London | 280 ppm | Hard | |
| TW16 | Sunbury On Thames | 280 ppm | Hard | |
| UB4 | Hayes | 280 ppm | Hard | |
| W13 | London | 280 ppm | Hard | |
| N16 | London | 279 ppm | Hard | |
| OX20 | Woodstock | 279 ppm | Hard | |
| TW15 | Ashford | 279 ppm | Hard | |
| UB3 | Hayes | 279 ppm | Hard | |
| W12 | London | 279 ppm | Hard | |
| N15 | London | 278 ppm | Hard | |
| TW14 | Feltham | 278 ppm | Hard | |
| UB2 | Southall | 278 ppm | Hard | |
| W11 | London | 278 ppm | Hard | |
| E18 | London | 277 ppm | Hard | |
| N14 | London | 277 ppm | Hard | |
| TW13 | Feltham | 277 ppm | Hard | |
| UB1 | Southall | 277 ppm | Hard | |
| W10 | London | 277 ppm | Hard | |
| E17 | London | 276 ppm | Hard | |
| N13 | London | 276 ppm | Hard | |
| TW12 | Hampton | 276 ppm | Hard | |
| E16 | London | 275 ppm | Hard | |
| N12 | London | 275 ppm | Hard | |
| TW11 | Teddington | 275 ppm | Hard | |
| E15 | London | 274 ppm | Hard | |
| N11 | London | 274 ppm | Hard | |
| TW10 | Richmond | 274 ppm | Hard | |
| E14 | London | 273 ppm | Hard | |
| N10 | London | 273 ppm | Hard | |
| E13 | London | 272 ppm | Hard | |
| E12 | London | 271 ppm | Hard | |
| GU19 | Bagshot | 271 ppm | Hard | |
| E11 | London | 270 ppm | Hard | |
| GU18 | Lightwater | 270 ppm | Hard | |
| E10 | London | 269 ppm | Hard | |
| GU17 | Camberley | 269 ppm | Hard | |
| RG19 | Thatcham | 269 ppm | Hard | |
| GU16 | Camberley | 268 ppm | Hard | |
| RG18 | Thatcham | 268 ppm | Hard | |
| GU15 | Camberley | 267 ppm | Hard | |
| GU47 | Sandhurst | 267 ppm | Hard | |
| RG17 | Hungerford | 267 ppm | Hard | |
| GU14 | Farnborough | 266 ppm | Hard | |
| GU46 | Yateley | 266 ppm | Hard | |
| GU12 | Aldershot | 264 ppm | Hard | |
| RG14 | Newbury | 264 ppm | Hard | |
| GU11 | Aldershot | 263 ppm | Hard | |
| RG45 | Crowthorne | 263 ppm | Hard | |
| DA18 | Erith | 262 ppm | Hard | |
| GU10 | Farnham | 262 ppm | Hard | |
| RG12 | Bracknell | 262 ppm | Hard | |
| RM20 | Grays | 262 ppm | Hard | |
| DA17 | Belvedere | 261 ppm | Hard | |
| HP19 | Aylesbury | 261 ppm | Hard | |
| DA16 | Welling | 260 ppm | Hard | |
| HP18 | Aylesbury | 260 ppm | Hard | |
| RG10 | Reading | 260 ppm | Hard | |
| RG42 | Bracknell | 260 ppm | Hard | |
| DA15 | Sidcup | 259 ppm | Hard | |
| HP17 | Aylesbury | 259 ppm | Hard | |
| RG41 | Wokingham | 259 ppm | Hard | |
| DA14 | Sidcup | 258 ppm | Hard | |
| HP16 | Great Missenden | 258 ppm | Hard | |
| RG40 | Wokingham | 258 ppm | Hard | |
| DA13 | Gravesend | 257 ppm | Hard | |
| HP15 | High Wycombe | 257 ppm | Hard | |
| DA12 | Gravesend | 256 ppm | Hard | |
| HP14 | High Wycombe | 256 ppm | Hard | |
| DA11 | Gravesend | 255 ppm | Hard | |
| HP13 | High Wycombe | 255 ppm | Hard | |
| SL9 | Gerrards Cross | 255 ppm | Hard | |
| DA10 | Swanscombe | 254 ppm | Hard | |
| HP12 | High Wycombe | 254 ppm | Hard | |
| OX18 | Carterton | 254 ppm | Hard | |
| SL8 | Bourne End | 254 ppm | Hard | |
| HP11 | High Wycombe | 253 ppm | Hard | |
| OX17 | Banbury | 253 ppm | Hard | |
| OX49 | Watlington | 253 ppm | Hard | |
| SL7 | Marlow | 253 ppm | Hard | |
| HP10 | High Wycombe | 252 ppm | Hard | |
| OX16 | Banbury | 252 ppm | Hard | |
| SL6 | Maidenhead | 252 ppm | Hard | |
| E9 | London | 251 ppm | Hard | |
| OX15 | Banbury | 251 ppm | Hard | |
| SL5 | Ascot | 251 ppm | Hard | |
| E8 | London | 250 ppm | Hard | |
| OX14 | Abingdon | 250 ppm | Hard | |
| SL4 | Windsor | 250 ppm | Hard |
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