How Portsmouth compares
At 277 mg/L (19.4 °Clark), Portsmouth is 14% above the median of the 411 English towns on this map (243 mg/L). It ranks 120 of 411 for hardness (1 is the hardest).
Water hardness in Portsmouth
Portsmouth has hard water: expect visible limescale and plan to descale regularly.
Data
| Value | 277 mg/L calcium carbonate 19.4 °Clark, 15.5 °dH |
|---|---|
| Band | hard |
| Area | Hampshire |
| Population | 208,100 |
| Water company | Portsmouth Water |
| Postcode checked | PO1 1FA (Farlington Central Supply Zone) |
| Checked | 21 Oct 2026 |
| From the source | “"NAME":"Farlington Central Supply Zone","HARDNESS":"Hard","CaCO3":277" (mg/l CaCO3),"ENGLISHDEG":19” |
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 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 Portsmouth?
The water company's figure for Portsmouth is 277 mg/L (19.4 °Clark), which is 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
Gosport 3 km Fareham 9 km Ryde 9 km Havant 10 km Waterlooville 10 km Cowes 15 km Sandown 17 km Newport 18 km