How Welwyn Garden City compares
At 319 mg/L (22.4 °Clark), Welwyn Garden City is 31% above the median of the 411 English towns on this map (243 mg/L). It ranks 40 of 411 for hardness (1 is the hardest).
Water hardness in Welwyn Garden City
Welwyn Garden City has very hard water: limescale builds up quickly, so descale often and protect your boiler.
Data
| Value | 319 mg/L calcium carbonate 22.4 °Clark, 17.9 °dH |
|---|---|
| Band | very hard |
| Area | Hertfordshire |
| Population | 51,505 |
| Water company | Affinity Water |
| Postcode checked | AL8 6AP |
| Checked | 21 Oct 2026 |
| From the source | “"Total Hardness":"319 mg/l","Calcium":"128 mg/l","Degrees English (Clarke)":"22.33","class":"very hard"” |
What it means for your home
Hard water drops a lot of scale when it is heated: in the kettle, the shower head and the element of an immersion heater or washing machine. Chalky rings on taps and spotty glasses are normal.
Set the dishwasher for hard water, dose detergent for your band and descale regularly. If you have a combi boiler, ask about a scale reducer at its next service. Hard water is safe to drink.
How often to descale
As a rule of thumb for very hard water, kettles and shower heads need descaling every three or four weeks. Descale whenever you see scale building up.
Common questions
Is hard water bad for you?
No. Hard water carries calcium and magnesium, minerals the body uses. Whether tap water is safe depends on germs and pollutants, which water companies test for, not on hardness.
Do I need a water softener in Welwyn Garden City?
The water company's figure for Welwyn Garden City is 319 mg/L (22.4 °Clark), which is very hard water. Usually not straight away. Set the dishwasher, dose detergent for your band and descale regularly. Get quotes for a softener only if scale is clearly damaging your boiler or appliances.
How do I find the value for my address?
Use your water company's postcode checker. Hardness can differ between districts, so check your own postcode, or test with strips or a drop test.
Nearby towns
Hatfield 4 km Hertford 9 km St Albans 10 km Harpenden 10 km Stevenage 11 km Potters Bar 12 km Hoddesdon 14 km Hadley Wood 15 km