Millions living in soft water areas could develop dementia

Millions of people may be up to a third more likely to develop dementia because of their tap water, new research has found.

A first-of-its-kind study suggests people who live in 'softer water' areas of the UK – 40 per cent of the UK population, around 27 million Britons – may be at increased risk of the degenerative disease because their drinking water contains lower levels of minerals such as calcium and magnesium.

Scientists suggest that these minerals may have a protective effect on the brain and say that low levels might also cause water pipes to corrode faster, allowing toxic elements such as lead to leach into the body.

Soft-water areas include Scotland, most of Yorkshire, Cornwall and the west and south coasts of Wales.

Meanwhile, thousands of people in hard-water areas install water softeners in their homes to remove magnesium and calcium and prevent limescale build-up.

The research found people with soft water had structural changes to their brain in 20 different areas, and may also be at risk from other neurodegenerative diseases such as multiple sclerosis.

The study was based on data from nearly 400,000 people in the UK and carried out by a team of scientists from Imperial College London and China.

Dr Tom Russ, director of the Alzheimer Scotland Dementia Research Centre, said: 'There is more work to be done on any environmental factor that might be linked to dementia, and this shows that water may potentially be a part of that. It's important to recognise that the study doesn't prove that water type contributes to the development of dementia.

'There's still a much bigger risk of dementia from other risk factors such as smoking, high cholesterol and high blood pressure and most people shouldn't be too worried about the effect that tap water might have. If it has any effect, it'll be very small.'

About one million people are living with some form of dementia in the UK. This is forecast to rise to 1.4 million by 2030.

Research suggests around 45 per cent of cases can be prevented by living a healthier lifestyle, challenging your brain and staying connected with other people.

Why some water is soft 

Water is either soft or hard due to the chemical elements within it - and that depends on geology.

Hard water is formed in areas with limestone or chalk, with rivers helping to release calcium and magnesium. It increases the amount of limescale that collects in kettles and washing machines.

Hard water is regarded as better for drinking as it has less sodium than soft water – but soft water is seen as kinder on the skin.

Scientists at King’s College London found that removing calcium and magnesium from the water supply can reduce irritation.

Homeowners can pay around £500 to switch their hot water supply from hard to soft. A soft-water convertor uses a resin to draw calcium and magnesium out of the water. They are then filtered out using a brine solution.

But there are thought to be other environmental factors, too.

Dr Russ's research has found links between areas with high levels of aluminium and fluoride in drinking water and an increased risk of dying from dementia.

Others have found a link between hard water and a reduced risk of heart disease.

But this latest study is one of the first to look at the impact of tap water's calcium content on neurodegenerative disease, and in the UK population.

Publishing their research, the scientists from the Shanghai Jiao Tong University School of Medicine wrote: 'We provide new evidence about the harmful effect of soft water on neurodegenerative diseases that highlight the importance of optimising water quality standards to ensure long-term health benefits.'

UK regulations do not specify standards for the level of minerals that should be contained in drinking water. Water is classed as either 'soft' or 'hard' depending on the local geology.

Around 60 per cent of tap water consumed in the UK is from areas with hard water.

The study was based on data taken from the UK Biobank, which performs ongoing research on 500,000 adults across the country. Scientists compared their home addresses and details of their water supply with the diagnosis of neurodegenerative diseases.

They found 2,389 people were diagnosed with Alzheimer's, 1,278 with vascular dementia and 366 with multiple sclerosis.

An analysis found that those exposed to soft water – defined as between zero and 60mg of calcium carbonate per litre of water – had a 34 per cent higher risk of vascular dementia compared with those who had a hard water supply, defined as between 120 and 300mg/L. Low concentrations of calcium were also associated with a 63 per cent higher risk of dementia more generally and a 53 per cent greater risk of MS.

Low levels of magnesium were associated with a 25 per cent higher risk of Alzheimer's.

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Brain scans of more than 30,000 people were also analysed to see if there were any physical differences. They found people living in areas with soft to moderately hard water had various parts of their brains that were reduced in volume compared with those living in hard water areas.

But Awad hesh Jha, Professor of Genetic Toxicology and Ecotoxicology at the University of Plymouth, said there were many factors involved in the development of diseases such as dementia.

'It is speculative to draw conclusions based on such associations and recommend regulations to maintain water hardness in drinking water,' he said.

The most populated parts of the UK, which include the South East, East England, the M4 corridor and most of the South Coast, live in hard water areas. The West Midlands, Liverpool, parts of Devon, Northumberland and East Wales have a medium-to-hard supply.

Dr Emma Anderson, Associate Professor of Epidemiology at King's College London, said the way the study was conducted was 'problematic'.

'Overall I think this is a poorly conducted study and not one we should be using to assess whether water hardness should be taken more seriously,' she added.