Scaling Up: Mapping The Areas Most Likely To Experience Hard Water Damage

Many people may be unaware of the hardness of the water in their homes, despite the impact it is having on their day-to-day lives. From the appearance of your drinking glasses in your cupboards and the suds in your washing machine to how your skin feels after washing your hands or having a shower, these unnoticed things can all be boiled down to how many calcium and magnesium ions are in your water supply.

While this isn’t usually a health hazard, the most significant impact that hard water can have is on your plumbing, central heating, and drainage. Scale can build up anywhere, with the potential to damage both cold and hot systems, including boilers, dishwashers and washing machines – causing corrosion, reduced flow rate and eventually blockages.

If particles of scale become suspended in the system and find their way into valves, they can damage them and cause leaks. Scale build-up causes damage to plumbing parts, such as flush mechanisms, pumps, and taps, meaning repairs and maintenance will become necessary.

In hot systems, scale building up on heating elements and inside radiators creates inefficiency in two ways: the overworking systems are more liable to breakdowns, and more energy is used in the heating process. This will mean that you will need to spend more on heating your property, which many are already struggling to afford right now, with energy bill costs higher than ever in the cost-of-living crisis.

In light of recent government policy, and news that the sale of gas boilers will be limited in the future, trying to extend the longevity of your boiler is in your best interest, to avoid having to change to potentially more expensive options and early replacement costs.

So, it’s important that you address the hard water in your home as soon as possible, to avoid spending unnecessary money – especially since damage claims caused by leaks in poorly maintained pipes might not be paid by insurance companies.

What can you do about the hardness of your water?

You can take measures to prevent these issues, ensuring the hot and cold systems within your property remain functional, maintain their efficiency and longevity, and require less maintenance.

If you live in an area with hard or very hard water, purchasing a water softener or water conditioner may solve these problems for you – and it will be much more affordable than paying for ongoing boiler repairs or locating and fixing any plumbing issues.

When our expert plumbers fit a water softener or conditioner, they are usually fitted on the water supply pipe after the main drinking tap. That way, you can drink unsoftened water from the mains supply.

The UK areas with the hardest water

Aspect has set out to discover which UK counties and London Boroughs have the hardest water.

To do this, we’ve used online tools to look at the water hardness score for each county and London Borough. These figures were then categorised into either soft, moderate, hard or very hard.

A water softener deals with hard water for a better shower

The London Boroughs with the hardest water

London BoroughWater Hardness figure (ppm)Category
Barnet327Very hard
Enfield315.5Very hard
Harrow304.8Very hard
Barking and Dagenham301Very hard
Kingston upon Thames295.8Very hard
Westminster295.3Very hard
Brent292.5Very hard
Richmond upon Thames291.6Very hard
Havering290Very hard
Hounslow288Very hard
Hillingdon285.8Very hard
Greenwich284Very hard
Redbridge283Very hard
Ealing281Very hard
Newham278Very hard
Haringey276Very hard
Waltham Forest276Very hard
Lewisham275Very hard
Hammersmith and Fulham274Very hard
Kensington and Chelsea271Very hard
Wandsworth271Very hard
Croydon271Very hard
Islington266Very hard
Hackney266Very hard
Merton261Very hard
Bromley257.9Very hard
Sutton252.8Very hard
Tower Hamlets252Very hard
Southwark251Very hard

All London Boroughs were found to have either hard or very hard water, with the majority being categorised as very hard.

The South East of the UK has predominantly chalk and limestone geology, which contributes to water hardness as it leads to high levels of calcium and magnesium in the water supply.

Of the 32 London Boroughs analysed, 9% had hard water, and 91% had very hard water. There were no London Boroughs which had either moderately hard or soft water.

The average water hardness score among the London Boroughs was 276, which falls into the very hard category.

The hardest water in London can be found in Barnet, with a score of 327, followed by Enfield, 315.5, and Harrow, 304.8.

Meanwhile, the London Borough with the softest water was Bexley with a score of 219.3, Lambeth with 236, and Camden with 245.7.

The UK counties with the hardest water

CountyWater Hardness figure (ppm)Category
Kent343Very hard
Cambridgeshire341Very hard
Gloucestershire341Very hard
Northamptonshire320Very hard
West Sussex319Very hard
Essex310Very hard
Bedfordshire300Very hard
Warwickshire300Very hard
Buckinghamshire286Very hard
Norfolk286Very hard
Hertfordshire280Very hard
Lincolnshire280Very hard
Nottinghamshire280Very hard
Oxfordshire280Very hard
Derbyshire278Very hard
Greater London274Very hard
Northumberland274Very hard
Tyne & Wear274Very hard
Dorset272Very hard
Shropshire270Very hard
East Sussex259Very hard
Rutland259Very hard
County Durham240Hard
Isle of Wight240Hard
South Gloucestershire228Hard
East Riding of Yorkshire219Hard
South Yorkshire210Hard
North Somerset200Moderate
West Midlands180Moderate
North Yorkshire157Moderate
West Yorkshire129Moderate
Greater Manchester110Moderate

Of the 49 counties which were analysed, only 2% had soft water, 29% had moderately hard water, 24% had hard water, and 46% had very hard water.

Only one county out of the 49 which were analysed, Cumbria, was found to have water which can be categorised as soft. This is because there is not much chalk to dissolve into the water in that area, resulting in a lower mineral content, as well as the heavy use of reservoirs in the area.

Many other Northern areas, including the West and North of Yorkshire, Manchester, Cheshire, and Lancashire, were found to have moderately hard water for the same reasons.

Meanwhile, South Yorkshire and East Yorkshire were found to have hard water. The level of water hardness tends to increase the further South East you go, and is known to vary across Yorkshire, due to the geology of the area.

Other counties which were found to have hard water include Leicestershire, Surrey, Worcestershire, Suffolk, South Gloucestershire, County Durham, Isle of Wight, Hampshire, Somerset and Wiltshire.

Many of the counties which were found to have very hard water, including Greater London, Dorset, Hertfordshire, and Essex, are in the Southern region of the UK, particularly in the South East, due to the chalk and limestone which is found in most of that area of the country.

Kent, the furthest South East county in the UK, has the highest water hardness score, 343, which also makes it the area of the UK with the hardest water overall.

James Hays, Technical Manager of Plumbing, Heating and AC at property maintenance experts Aspect, said: “While hard water isn’t usually a risk to your health, it can have a significant effect on plumbing fixtures, causing corrosion, damage and reduced functionality, and increasing the risk of water leaks.

“The vast majority of us live in hard water areas, where the bedrock is made of sedimentary rocks like limestone, chalk, flint and sandstone. The South East of the UK is mainly made up of chalk and limestone regions and as a result, has the hardest water. This can be seen in the findings of our research, with areas in the South East of the UK, such as Kent, Cambridgeshire, and London, all scoring highly.

“The good news is that there are measures that you can take to help protect your plumbing fixtures from these issues, ensuring they remain both functional and visually appealing. If you live in an area with hard or very hard water, purchasing a water softener may solve these problems for you, by replacing the hardness in the water with sodium ions. It is essential that you make sure that it is installed by a qualified plumber, to make sure that it is done correctly and safely.”

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