Water Hardness in Greater London

Water Hardness Across Greater London

The average water hardness in Greater London is 302 ppm, classified as very hard. Across 330 postcode districts in the London region, hardness ranges from 224 ppm to 350 ppm.

Greater London is served by Affinity Water and SES Water and South East Water and Thames Water. With very hard water, residents may benefit from a water softener to reduce limescale and protect appliances.

Hardness varies across Greater London: Wembley has the hardest water at 332 ppm, while Watford is the softest at 233 ppm. The county spans 13 towns and 330 postcode districts in total.

At 302 ppm, Greater London ranks as very hard water nationally. Compare it against the 50 hardest water areas in the UK.

Towns in Greater London

Sorted by hardness. Tap a town for full details.

Town	Hardness	PPM	Level
Wembley	332	332 ppm	Very Hard
Enfield	325	325 ppm	Very Hard
Romford	318	318 ppm	Very Hard
Ilford	310	310 ppm	Very Hard
Kingston Upon Thames	310	310 ppm	Very Hard
London	306	306 ppm	Very Hard
Bromley	297	297 ppm	Hard
Croydon	297	297 ppm	Hard
Dartford	289	289 ppm	Hard
Southall	287	287 ppm	Hard
Twickenham	284	284 ppm	Hard
Sutton	239	239 ppm	Hard
Watford	233	233 ppm	Hard

Postcodes in Greater London

Every postcode district in the county, sorted by hardness.

Postcode	Town	Hardness	PPM	Level
E7	London	350	350 ppm	Very Hard
E6	London	349	349 ppm	Very Hard
E5	London	348	348 ppm	Very Hard
E4	London	347	347 ppm	Very Hard
E3	London	346	346 ppm	Very Hard
EN9	Waltham Abbey	346	346 ppm	Very Hard
KT24	Leatherhead	346	346 ppm	Very Hard
N9	London	346	346 ppm	Very Hard
E2	London	345	345 ppm	Very Hard
EN8	Waltham Cross	345	345 ppm	Very Hard
KT23	Leatherhead	345	345 ppm	Very Hard
N8	London	345	345 ppm	Very Hard
E1	London	344	344 ppm	Very Hard
EN7	Waltham Cross	344	344 ppm	Very Hard
KT22	Leatherhead	344	344 ppm	Very Hard
N7	London	344	344 ppm	Very Hard
EN6	Potters Bar	343	343 ppm	Very Hard
KT21	Ashtead	343	343 ppm	Very Hard
N6	London	343	343 ppm	Very Hard
EC2A	London	342	342 ppm	Very Hard
EN5	Barnet	342	342 ppm	Very Hard
KT20	Tadworth	342	342 ppm	Very Hard
N5	London	342	342 ppm	Very Hard
EN4	Barnet	341	341 ppm	Very Hard
N4	London	341	341 ppm	Very Hard
EN3	Enfield	340	340 ppm	Very Hard
N3	London	340	340 ppm	Very Hard
W9	London	340	340 ppm	Very Hard
EN2	Enfield	339	339 ppm	Very Hard
N2	London	339	339 ppm	Very Hard
RM19	Purfleet On Thames	339	339 ppm	Very Hard
W8	London	339	339 ppm	Very Hard
EN1	Enfield	338	338 ppm	Very Hard
N1	London	338	338 ppm	Very Hard
RM18	Tilbury	338	338 ppm	Very Hard
W7	London	338	338 ppm	Very Hard
RM17	Grays	337	337 ppm	Very Hard
W6	London	337	337 ppm	Very Hard
HA9	Wembley	336	336 ppm	Very Hard
RM16	Grays	336	336 ppm	Very Hard
W5	London	336	336 ppm	Very Hard
HA8	Edgware	335	335 ppm	Very Hard
RM15	South Ockendon	335	335 ppm	Very Hard
W4	London	335	335 ppm	Very Hard
HA7	Stanmore	334	334 ppm	Very Hard
RM14	Upminster	334	334 ppm	Very Hard
SW1Y	London	334	334 ppm	Very Hard
W3	London	334	334 ppm	Very Hard
EC1Y	London	333	333 ppm	Very Hard
HA6	Northwood	333	333 ppm	Very Hard
RM13	Rainham	333	333 ppm	Very Hard
SW1X	London	333	333 ppm	Very Hard
W2	London	333	333 ppm	Very Hard
HA5	Pinner	332	332 ppm	Very Hard
RM12	Hornchurch	332	332 ppm	Very Hard
SW1W	London	332	332 ppm	Very Hard
EC4Y	London	331	331 ppm	Very Hard
HA4	Ruislip	331	331 ppm	Very Hard
IG11	Barking	331	331 ppm	Very Hard
RM11	Hornchurch	331	331 ppm	Very Hard
SW1V	London	331	331 ppm	Very Hard
EC1V	London	330	330 ppm	Very Hard
HA3	Harrow	330	330 ppm	Very Hard
IG10	Loughton	330	330 ppm	Very Hard
RM10	Dagenham	330	330 ppm	Very Hard
HA2	Harrow	329	329 ppm	Very Hard
EC4V	London	328	328 ppm	Very Hard
HA1	Harrow	328	328 ppm	Very Hard
HA0	Wembley	327	327 ppm	Very Hard
SE9	London	327	327 ppm	Very Hard
EC1R	London	326	326 ppm	Very Hard
SE28	London	326	326 ppm	Very Hard
SE8	London	326	326 ppm	Very Hard
SW20	London	326	326 ppm	Very Hard
SE27	London	325	325 ppm	Very Hard
SE7	London	325	325 ppm	Very Hard
SW1P	London	325	325 ppm	Very Hard
EC4R	London	324	324 ppm	Very Hard
NW9	London	324	324 ppm	Very Hard
SE26	London	324	324 ppm	Very Hard
SE6	London	324	324 ppm	Very Hard
DA9	Greenhithe	323	323 ppm	Very Hard
NW8	London	323	323 ppm	Very Hard
SE25	London	323	323 ppm	Very Hard
SE5	London	323	323 ppm	Very Hard
DA8	Erith	322	322 ppm	Very Hard
EC1N	London	322	322 ppm	Very Hard
NW7	London	322	322 ppm	Very Hard
SE24	London	322	322 ppm	Very Hard
SE4	London	322	322 ppm	Very Hard
DA7	Bexleyheath	321	321 ppm	Very Hard
EC1M	London	321	321 ppm	Very Hard
NW6	London	321	321 ppm	Very Hard
SE23	London	321	321 ppm	Very Hard
SE3	London	321	321 ppm	Very Hard
DA6	Bexleyheath	320	320 ppm	Very Hard
EC4N	London	320	320 ppm	Very Hard
NW5	London	320	320 ppm	Very Hard
SE2	London	320	320 ppm	Very Hard
SE22	London	320	320 ppm	Very Hard
WC2R	London	320	320 ppm	Very Hard
DA5	Bexley	319	319 ppm	Very Hard
EC4M	London	319	319 ppm	Very Hard
NW4	London	319	319 ppm	Very Hard
SE1	London	319	319 ppm	Very Hard
SE21	London	319	319 ppm	Very Hard
DA4	Dartford	318	318 ppm	Very Hard
KT19	Epsom	318	318 ppm	Very Hard
NW3	London	318	318 ppm	Very Hard
SE20	London	318	318 ppm	Very Hard
DA3	Longfield	317	317 ppm	Very Hard
KT18	Epsom	317	317 ppm	Very Hard
NW2	London	317	317 ppm	Very Hard
SW1H	London	317	317 ppm	Very Hard
DA2	Dartford	316	316 ppm	Very Hard
KT17	Epsom	316	316 ppm	Very Hard
NW1	London	316	316 ppm	Very Hard
W1W	London	316	316 ppm	Very Hard
WC2N	London	316	316 ppm	Very Hard
DA1	Dartford	315	315 ppm	Very Hard
KT16	Chertsey	315	315 ppm	Very Hard
SW9	London	315	315 ppm	Very Hard
KT15	Addlestone	314	314 ppm	Very Hard
SW1E	London	314	314 ppm	Very Hard
SW8	London	314	314 ppm	Very Hard
UB11	Uxbridge	314	314 ppm	Very Hard
W1U	London	314	314 ppm	Very Hard
KT14	West Byfleet	313	313 ppm	Very Hard
SW7	London	313	313 ppm	Very Hard
UB10	Uxbridge	313	313 ppm	Very Hard
W1T	London	313	313 ppm	Very Hard
KT13	Weybridge	312	312 ppm	Very Hard
SW6	London	312	312 ppm	Very Hard
W1S	London	312	312 ppm	Very Hard
KT12	Walton On Thames	311	311 ppm	Very Hard
SW5	London	311	311 ppm	Very Hard
IG9	Buckhurst Hill	310	310 ppm	Very Hard
KT11	Cobham	310	310 ppm	Very Hard
RM9	Dagenham	310	310 ppm	Very Hard
SW1A	London	310	310 ppm	Very Hard
SW4	London	310	310 ppm	Very Hard
WC2H	London	310	310 ppm	Very Hard
EC1A	London	309	309 ppm	Very Hard
IG8	Woodford Green	309	309 ppm	Very Hard
KT10	Esher	309	309 ppm	Very Hard
RM8	Dagenham	309	309 ppm	Very Hard
SW3	London	309	309 ppm	Very Hard
E1W	London	308	308 ppm	Very Hard
IG7	Chigwell	308	308 ppm	Very Hard
N22	London	308	308 ppm	Very Hard
RM7	Romford	308	308 ppm	Very Hard
SW2	London	308	308 ppm	Very Hard
EC4A	London	307	307 ppm	Very Hard
IG6	Ilford	307	307 ppm	Very Hard
N21	London	307	307 ppm	Very Hard
RM6	Romford	307	307 ppm	Very Hard
TW20	Egham	307	307 ppm	Very Hard
WC2E	London	307	307 ppm	Very Hard
IG5	Ilford	306	306 ppm	Very Hard
N20	London	306	306 ppm	Very Hard
RM5	Romford	306	306 ppm	Very Hard
IG4	Ilford	305	305 ppm	Very Hard
RM4	Romford	305	305 ppm	Very Hard
IG3	Ilford	304	304 ppm	Very Hard
RM3	Romford	304	304 ppm	Very Hard
W1K	London	304	304 ppm	Very Hard
WC2B	London	304	304 ppm	Very Hard
IG2	Ilford	303	303 ppm	Very Hard
RM2	Romford	303	303 ppm	Very Hard
W1J	London	303	303 ppm	Very Hard
WC2A	London	303	303 ppm	Very Hard
E20	Olympic Park	302	302 ppm	Very Hard
IG1	Ilford	302	302 ppm	Very Hard
RM1	Romford	302	302 ppm	Very Hard
SW19	London	302	302 ppm	Very Hard
CR9	Croydon	301	301 ppm	Very Hard
SW18	London	301	301 ppm	Very Hard
W1H	London	301	301 ppm	Very Hard
BR8	Swanley	300	300 ppm	Hard
CR8	Purley	300	300 ppm	Hard
SW17	London	300	300 ppm	Hard
W1G	London	300	300 ppm	Hard
BR7	Chislehurst	299	299 ppm	Hard
CR7	Thornton Heath	299	299 ppm	Hard
SW16	London	299	299 ppm	Hard
W1F	London	299	299 ppm	Hard
BR6	Orpington	298	298 ppm	Hard
CR6	Warlingham	298	298 ppm	Hard
SW15	London	298	298 ppm	Hard
BR5	Orpington	297	297 ppm	Hard
CR5	Coulsdon	297	297 ppm	Hard
SW14	London	297	297 ppm	Hard
W1D	London	297	297 ppm	Hard
BR4	West Wickham	296	296 ppm	Hard
CR4	Mitcham	296	296 ppm	Hard
SW13	London	296	296 ppm	Hard
W1C	London	296	296 ppm	Hard
BR3	Beckenham	295	295 ppm	Hard
CR3	Caterham	295	295 ppm	Hard
EC3V	London	295	295 ppm	Hard
SW12	London	295	295 ppm	Hard
W1B	London	295	295 ppm	Hard
BR2	Bromley	294	294 ppm	Hard
CR2	South Croydon	294	294 ppm	Hard
SE19	London	294	294 ppm	Hard
SW11	London	294	294 ppm	Hard
BR1	Bromley	293	293 ppm	Hard
SE18	London	293	293 ppm	Hard
SW10	London	293	293 ppm	Hard
TW9	Richmond	293	293 ppm	Hard
WC1X	London	293	293 ppm	Hard
CR0	Croydon	292	292 ppm	Hard
N1C	London	292	292 ppm	Hard
SE17	London	292	292 ppm	Hard
TW8	Brentford	292	292 ppm	Hard
EC3R	London	291	291 ppm	Hard
KT9	Chessington	291	291 ppm	Hard
SE16	London	291	291 ppm	Hard
TW7	Isleworth	291	291 ppm	Hard
WC1V	London	291	291 ppm	Hard
KT8	West Molesey	290	290 ppm	Hard
SE15	London	290	290 ppm	Hard
KT7	Thames Ditton	289	289 ppm	Hard
SE14	London	289	289 ppm	Hard
TW5	Hounslow	289	289 ppm	Hard
KT6	Surbiton	288	288 ppm	Hard
NW11	London	288	288 ppm	Hard
SE13	London	288	288 ppm	Hard
TW4	Hounslow	288	288 ppm	Hard
EC3N	London	287	287 ppm	Hard
KT5	Surbiton	287	287 ppm	Hard
NW10	London	287	287 ppm	Hard
SE12	London	287	287 ppm	Hard
TW3	Hounslow	287	287 ppm	Hard
WC1R	London	287	287 ppm	Hard
EC3M	London	286	286 ppm	Hard
KT4	Worcester Park	286	286 ppm	Hard
SE11	London	286	286 ppm	Hard
TW2	Twickenham	286	286 ppm	Hard
KT3	New Malden	285	285 ppm	Hard
SE10	London	285	285 ppm	Hard
TW1	Twickenham	285	285 ppm	Hard
UB9	Uxbridge	285	285 ppm	Hard
KT2	Kingston Upon Thames	284	284 ppm	Hard
UB8	Uxbridge	284	284 ppm	Hard
KT1	Kingston Upon Thames	283	283 ppm	Hard
TW19	Staines Upon Thames	283	283 ppm	Hard
UB7	West Drayton	283	283 ppm	Hard
WC1N	London	283	283 ppm	Hard
N19	London	282	282 ppm	Hard
TW18	Staines Upon Thames	282	282 ppm	Hard
UB6	Greenford	282	282 ppm	Hard
N18	London	281	281 ppm	Hard
TW17	Shepperton	281	281 ppm	Hard
UB5	Northolt	281	281 ppm	Hard
W14	London	281	281 ppm	Hard
N17	London	280	280 ppm	Hard
TW16	Sunbury On Thames	280	280 ppm	Hard
UB4	Hayes	280	280 ppm	Hard
W13	London	280	280 ppm	Hard
N16	London	279	279 ppm	Hard
TW15	Ashford	279	279 ppm	Hard
UB3	Hayes	279	279 ppm	Hard
W12	London	279	279 ppm	Hard
N15	London	278	278 ppm	Hard
TW14	Feltham	278	278 ppm	Hard
UB2	Southall	278	278 ppm	Hard
W11	London	278	278 ppm	Hard
E18	London	277	277 ppm	Hard
N14	London	277	277 ppm	Hard
TW13	Feltham	277	277 ppm	Hard
UB1	Southall	277	277 ppm	Hard
W10	London	277	277 ppm	Hard
WC1H	London	277	277 ppm	Hard
E17	London	276	276 ppm	Hard
N13	London	276	276 ppm	Hard
TW12	Hampton	276	276 ppm	Hard
E16	London	275	275 ppm	Hard
N12	London	275	275 ppm	Hard
TW11	Teddington	275	275 ppm	Hard
E15	London	274	274 ppm	Hard
EC3A	London	274	274 ppm	Hard
N11	London	274	274 ppm	Hard
TW10	Richmond	274	274 ppm	Hard
WC1E	London	274	274 ppm	Hard
E14	London	273	273 ppm	Hard
N10	London	273	273 ppm	Hard
E13	London	272	272 ppm	Hard
E12	London	271	271 ppm	Hard
WC1B	London	271	271 ppm	Hard
E11	London	270	270 ppm	Hard
WC1A	London	270	270 ppm	Hard
E10	London	269	269 ppm	Hard
EC2Y	London	265	265 ppm	Hard
DA18	Erith	262	262 ppm	Hard
EC2V	London	262	262 ppm	Hard
RM20	Grays	262	262 ppm	Hard
DA17	Belvedere	261	261 ppm	Hard
DA16	Welling	260	260 ppm	Hard
DA15	Sidcup	259	259 ppm	Hard
DA14	Sidcup	258	258 ppm	Hard
EC2R	London	258	258 ppm	Hard
DA13	Gravesend	257	257 ppm	Hard
DA12	Gravesend	256	256 ppm	Hard
DA11	Gravesend	255	255 ppm	Hard
WD25	Watford	255	255 ppm	Hard
DA10	Swanscombe	254	254 ppm	Hard
EC2N	London	254	254 ppm	Hard
WD24	Watford	254	254 ppm	Hard
EC2M	London	253	253 ppm	Hard
WD23	Bushey	253	253 ppm	Hard
E9	London	251	251 ppm	Hard
E8	London	250	250 ppm	Hard
EN11	Hoddesdon	247	247 ppm	Hard
EN10	Broxbourne	246	246 ppm	Hard
SM7	Banstead	242	242 ppm	Hard
SM6	Wallington	241	241 ppm	Hard
SM5	Carshalton	240	240 ppm	Hard
SM4	Morden	239	239 ppm	Hard
SM3	Sutton	238	238 ppm	Hard
SM2	Sutton	237	237 ppm	Hard
SM1	Sutton	236	236 ppm	Hard
WD7	Radlett	228	228 ppm	Hard
WD6	Borehamwood	227	227 ppm	Hard
WD19	Watford	226	226 ppm	Hard
WD5	Abbots Langley	226	226 ppm	Hard
WD18	Watford	225	225 ppm	Hard
WD4	Kings Langley	225	225 ppm	Hard
WD17	Watford	224	224 ppm	Hard
WD3	Rickmansworth	224	224 ppm	Hard

Products for Greater London

Top picks for households in very hard water areas.

Splendid Twin Tank Water Softener

Twin-tank electric softener sized for 1 to 7 bedroom homes. Removes limescale from pipes, boilers, and appliances and delivers continuous soft water, with metered regeneration to keep salt use low.

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Philips Shower Filter

Instant improvement for skin and hair. Reduces chlorine and limescale at the showerhead, no plumbing needed. A good first step before committing to a full softener.

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Water Hardness in Greater London: Common Questions

Is the water in Greater London hard or soft?

Greater London has very hard water, averaging 302 ppm across 330 postcode districts. Expect visible limescale on kettles, taps and shower screens within weeks at this level.

Where is the hardest water in Greater London?

Wembley has the hardest water in Greater London at 332 ppm, while Watford is the softest at 233 ppm. Across the county, hardness ranges from 224 ppm to 350 ppm by postcode district.

Which water company supplies Greater London?

Greater London is supplied by Affinity Water and SES Water and South East Water and Thames Water. You can check each supplier's reported hardness figures on their water company page.

Do I need a water softener in Greater London?

At 302 ppm, Greater London is in the hard band where a water softener noticeably reduces limescale and helps protect boilers and appliances. See the water softener guide for the payback maths.

What is the average water hardness in Greater London?

The average water hardness in Greater London is 302 ppm (parts per million), classified as very hard. It ranges from 224 ppm to 350 ppm across 330 postcode districts in the London region.

Get free water softener quotes

Water Hardness Across Greater London

Central London Water Hardness

Towns in Greater London

Water Companies in Greater London

Affinity Water

SES Water

South East Water

Thames Water

Postcodes in Greater London

Products for Greater London

Splendid Twin Tank Water Softener

Philips Shower Filter

Water Hardness in Greater London: Common Questions

Hard Water Guides