South East · County

Water hardness in Hertfordshire

Average 303 ppm across 53 postcodes and 3 towns.

Range 239–378 ppm
Towns 3
Suppliers Affinity Water, Anglian Water, Thames Water

County average

303

ppm CaCO₃

Very Hard

Soft

Moderate

Hard

Very hard

0100200300400+

303

Avg ppm

239

Min ppm

378

Max ppm

Postcodes

Water Hardness Across Hertfordshire

The average water hardness in Hertfordshire is 303 ppm, classified as very hard. Across 53 postcode districts in the South East region, hardness ranges from 239 ppm to 378 ppm.

Hertfordshire is served by Affinity Water and Anglian Water and Thames Water. With very hard water, residents may benefit from a water softener to reduce limescale and protect appliances.

By town

Towns in Hertfordshire

Sorted by hardness — tap a town for full details.

Town	Hardness	PPM	Level
Stevenage	352	352 ppm	Very Hard
Hemel Hempstead	288	288 ppm	Hard
St Albans	244	244 ppm	Hard

Suppliers

Water Companies in Hertfordshire

Companies supplying water to this county.

All postcodes

Postcodes in Hertfordshire

Every postcode district in the county, sorted by hardness.

Postcode	Town	Hardness	PPM	Level
SG9	Buntingford	378	378 ppm	Very Hard
SG8	Royston	377	377 ppm	Very Hard
SG7	Baldock	376	376 ppm	Very Hard
SG6	Letchworth Garden City	375	375 ppm	Very Hard
SG5	Hitchin	374	374 ppm	Very Hard
SG4	Hitchin	373	373 ppm	Very Hard
SG3	Knebworth	372	372 ppm	Very Hard
SG2	Stevenage	371	371 ppm	Very Hard
SG1	Stevenage	370	370 ppm	Very Hard
SG19	Sandy	337	337 ppm	Very Hard
SG18	Biggleswade	336	336 ppm	Very Hard
SG17	Shefford	335	335 ppm	Very Hard
SG16	Henlow	334	334 ppm	Very Hard
SG15	Arlesey	333	333 ppm	Very Hard
SG14	Hertford	332	332 ppm	Very Hard
SG13	Hertford	331	331 ppm	Very Hard
SG12	Ware	330	330 ppm	Very Hard
SG11	Ware	329	329 ppm	Very Hard
SG10	Much Hadham	328	328 ppm	Very Hard
HP9	Beaconsfield	326	326 ppm	Very Hard
HP8	Chalfont St Giles	325	325 ppm	Very Hard
HP7	Amersham	324	324 ppm	Very Hard
HP6	Amersham	323	323 ppm	Very Hard
HP5	Chesham	322	322 ppm	Very Hard
HP4	Berkhamsted	321	321 ppm	Very Hard
HP3	Hemel Hempstead	320	320 ppm	Very Hard
HP2	Hemel Hempstead	319	319 ppm	Very Hard
HP1	Hemel Hempstead	318	318 ppm	Very Hard
HP27	Princes Risborough	292	292 ppm	Hard
HP23	Tring	288	288 ppm	Hard
HP22	Aylesbury	287	287 ppm	Hard
HP21	Aylesbury	286	286 ppm	Hard
HP20	Aylesbury	285	285 ppm	Hard
HP19	Aylesbury	261	261 ppm	Hard
HP18	Aylesbury	260	260 ppm	Hard
HP17	Aylesbury	259	259 ppm	Hard
HP16	Great Missenden	258	258 ppm	Hard
HP15	High Wycombe	257	257 ppm	Hard
HP14	High Wycombe	256	256 ppm	Hard
HP13	High Wycombe	255	255 ppm	Hard
AL10	Hatfield	254	254 ppm	Hard
HP12	High Wycombe	254	254 ppm	Hard
HP11	High Wycombe	253	253 ppm	Hard
HP10	High Wycombe	252	252 ppm	Hard
AL9	Hatfield	247	247 ppm	Hard
AL8	Welwyn Garden City	246	246 ppm	Hard
AL7	Welwyn Garden City	245	245 ppm	Hard
AL6	Welwyn	244	244 ppm	Hard
AL5	Harpenden	243	243 ppm	Hard
AL4	St Albans	242	242 ppm	Hard
AL3	St Albans	241	241 ppm	Hard
AL2	St Albans	240	240 ppm	Hard
AL1	St Albans	239	239 ppm	Hard

Recommended

Products for Hertfordshire

Top picks for households in very hard water areas.

Water2Buy W2B200 Water Softener

From ~£400

Best-value whole-house ion-exchange softener for UK homes. Eliminates limescale from pipes, boilers, and appliances. Digital metered regeneration — low salt use. 7-year warranty.

View on Amazon

Philips AWP1775 Shower Filter

From ~£30

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.

View on Amazon

Hard Water Guides

Learn more about water hardness and how to manage it.

What Is Water Hardness? Hard Water Effects Solutions

All counties in South East · Hardest water areas · Softest water areas · Hard water solutions

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