Could a water filter do you more harm than good?


From the filter jug that claims to be so good it can turn red wine back into water, to drinking bottles with sticks of ‘activated’ carbon that attract ‘contaminants’, there’s a whole new generation of gadgets promising purer eau de tap.

But do we really need to bother? And, in fact, far from being ‘healthier’, could we be doing more harm than good?

Tap water in the UK is among the safest in the world, according to Dr Jim Marshall, senior policy adviser at Water UK. ‘It passes more than 99.9 per cent of quality tests. As a result, there are no specific health benefits to water filters and their use is a matter of personal preference.’

A whole new generation of filtration gadgets are promising purer tap water, with some even promising to turn red wine into H20

A whole new generation of filtration gadgets are promising purer tap water, with some even promising to turn red wine into H20

A whole new generation of filtration gadgets are promising purer tap water, with some even promising to turn red wine into H20

Yet there are still fears about the possible presence of toxins such as lead and microscopic plastic fibres. However, many of the health benefits of filters are implied rather than explicit.

Brita, for example, focuses on improving ‘taste’, ‘freshness’ and reducing water hardness — the calcium deposits which cause limescale.

Its Brita Fill And Enjoy Style jug (£31) boasts ‘premium limescale reduction’ and comes with test strips to measure how hard your water is.

However, hard water is not bad for you — only for your kettle. In fact, research collated by the World Health Organisation (WHO) confirmed a correlation between drinking harder water and lower rates of heart disease.

One new brand of water filter, ZeroWater (£24.99), has a five-step filter that claims to remove ‘virtually all’ traces of dissolved solids such as mercury, lead and fluoride. It says it can even turn wine back into plain water (we tested it — it works).

But some experts say there are no health benefits to using the appliances and insist that tap water in the UK is among the safest and highest quality in the world

But some experts say there are no health benefits to using the appliances and insist that tap water in the UK is among the safest and highest quality in the world

But some experts say there are no health benefits to using the appliances and insist that tap water in the UK is among the safest and highest quality in the world

Along with its jug, ZeroWater includes a TDS (total dissolved solids) meter, so you can test the claims for yourself. But the amount and composition of dissolved solids in your tap water varies. A relatively high TDS reading could be because you live in a hard water area, rather than being a sign anything ‘bad’ is lurking.

In other words, there’s no way of knowing how much of the dissolved material removed is harmful, and how much is innocuous, or even beneficial.

A bottle of mineral water would have a fairly high TDS reading — yet those very minerals are one of its selling points. Evian has 357mg TDS per litre, including 78mg of calcium and 24mg magnesium.

‘This kind of thing has more to do with trends than definite benefits for health,’ says Linia Patel, of the British Dietetic Association. ‘It’s worth asking, “Why is it meant to be a good thing to drink bottled water containing these minerals, yet so-and-so is saying remove all possible minerals with a filter?’

World Health Organisation (WHO) even confirmed a correlation between drinking harder water and lower rates of heart disease

World Health Organisation (WHO) even confirmed a correlation between drinking harder water and lower rates of heart disease

World Health Organisation (WHO) even confirmed a correlation between drinking harder water and lower rates of heart disease

But what about scarier-sounding substances, such as lead? In fact, lead has been all but eradicated from our main water pipes, according to the Drinking Water Inspectorate (DWI).

As for chlorine, which is used as a disinfectant, a ‘residual’ amount does remain to keep water clear of microorganisms. In large quantities it’s an irritant, but Sue Pennison, principal inspector at the DWI, says the residual amount is safe to drink. The main issue is that many people don’t like the taste chlorine leaves.

Some filters, such as the bottles sold by Black + Blum (from £19.95), contain ‘activated’ charcoal to draw chlorine out of the water, improving the taste. While these will work, says Linia Patel, you could just leave water in a normal jug in the fridge for 12 to 24 hours. ‘Chlorine is a gas which, given time, will dissipate on its own,’ adds Sue Pennison.

There are some substances neither water companies nor filter manufacturers know if they can remove effectively — microscopic plastic fibres. These were found in 72 per cent of European drinking water samples in a study by Orb Media, published last year.

The concern is these might leach phthalates, chemicals that can disrupt our hormonal systems. ‘Our treatment systems are set up to remove very small particles from water, but we do recognise that [microplastics] is perhaps an area where there isn’t that much evidence or research, so we are commissioning some due to public concern,’ says Sue Pennison.

In some circumstances, using a water filter might be detrimental to health. The ZeroWater filter claims to remove fluoride completely, but as Professor Damien Walmsley, the British Dental Association’s scientific adviser, explains: ‘Drinking filtered water regularly could mean people miss out on the benefits of [added] fluoride that protect teeth from decay.’

There is also a potential hygiene risk. ‘One of the downsides of filters is keeping them maintained,’ warns Sue Pennison. ‘If you don’t, they can become a hazard in themselves because the filter can grow mould and break down and impart material in to the water.’

Dr Marshall advises following manufacturers’ instructions to the letter, ‘as unmaintained filters can have a detrimental impact on water quality’.

Black + Blum recommends ‘re-activating’ its charcoal by boiling for ten minutes after three months, then disposing of it after a further three. It advises not to leave water in the bottle for more than one day, as when left ‘for long periods, mould spores can form’.

The manufacturer also notes: ‘The charcoal removes the chlorine from drinking water, so you might notice [mould] forming even quicker than normal.’

Suddenly, plain old tap water doesn’t seem so bad after all.

 



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