UK Water Hardness Map: How Hard is Your Water?

UK Water Hardness by Region

Water hardness in the UK is largely determined by geology. The South East sits on chalk and limestone, which dissolves calcium carbonate into the water supply. The North and West have older, harder rock formations like granite and slate that don't add minerals.

Regional Overview

Very Hard Water (above 200 mg/l)

London, the Home Counties, Kent, Sussex, Essex, Norfolk, Suffolk, Cambridgeshire, Bedfordshire, and Hertfordshire. Water companies: Thames Water, Affinity Water, South East Water, Anglian Water, SES Water. These areas draw water from deep chalk aquifers and the River Thames.

Hard Water (120 - 200 mg/l)

Much of the East Midlands, parts of Yorkshire, Hampshire, and Wiltshire. Water companies: Severn Trent (eastern zones), Anglian Water (western zones), Southern Water, Wessex Water. A mix of chalk and sandstone geology.

Moderately Hard Water (60 - 120 mg/l)

Parts of the West Midlands, South West, and Northern England. Water companies: Severn Trent (western zones), Bristol Water, Northumbrian Water, Portsmouth Water. Mixed geology with some limestone influence.

Soft Water (below 60 mg/l)

Scotland, Wales, the Lake District, Devon, Cornwall, and parts of Northumberland. Water companies: Scottish Water, Welsh Water, United Utilities, South West Water. These regions have granite, slate, and volcanic rock that don't dissolve minerals into the water.

Check Your Exact Hardness

Regional maps give a general picture, but hardness can vary street by street depending on which supply zone you're in. Enter your postcode on WaterGrade for the exact hardness measurement from your water company.

Why Hardness Matters

Hard water causes limescale in kettles and boilers, reduces soap effectiveness, and can affect hair and skin. Knowing your hardness level helps you decide whether a water softener, filter jug, or descaling routine is worthwhile. See our full hardness guide and hard water and hair guide for more detail.

Frequently Asked Questions

Where is water hardest in the UK?

The hardest water in the UK is found in the South East and East of England, particularly in areas supplied by Thames Water, Affinity Water, South East Water, and Anglian Water. London, Kent, Sussex, Essex, Norfolk, and Suffolk typically have hardness levels above 200 mg/l, with some areas exceeding 300 mg/l.

Where is water softest in the UK?

The softest water in the UK is found in Scotland, Wales, the Lake District, and the South West peninsula (Devon and Cornwall). These areas have granite and slate rock formations that don't dissolve minerals into the water supply. Hardness is typically below 50 mg/l.

Why does water hardness vary across the UK?

Water hardness is determined by local geology. In the South East, the underground chalk and limestone formations dissolve calcium carbonate into the water supply, making it hard. In the North and West, older granite and volcanic rock formations don't dissolve, so the water stays soft.

Does my water company affect hardness?

Your water company determines where your water comes from, which determines its hardness. Companies like Thames Water and Anglian Water draw from chalk aquifers (hard water), while Scottish Water and United Utilities source from upland reservoirs (soft water). Some companies serve areas with mixed hardness levels.

Check Your Water Quality

Enter your UK postcode for an instant water quality report graded A-F.

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