Could a ‘healthy’ 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?

Ireland has a very high standard of tap water quality, with Irish Water treating more than 1.7 billion litres of drinking water every day. The authority told Good Health its utility has a standardised system of regular testing of treated drinking water to ensure compliance with all drinking water parameters, the results of which can be viewed on water.ie.

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 (€34) 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, 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). Along with its jug, ZeroWater (€44.60, amazon.co.uk) includes a TDS (total dissolved solids) meter, so you can test the claims 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, a leading dietitian.

‘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?’ But what about scariersounding substances, like lead?

Irish Water says: ‘When water leaves our treatment plants it is lead free and our records show that there are no lead public water mains in Ireland.

‘However, lead plumbing was widely used in houses built before the 1980s. It is estimated that 180,000 homes in Ireland together with public buildings, schools, medical centres and other buildings over 40 years old, may have lead plumbing.’

The authority says it ‘recognises that the most effective long-term strategy is to remove all lead pipes and fittings from the entire drinking water supply network. This is also the recommendation of the World Health Organisation.’

As such, the majority of lead pipes currently in existence in Ireland are on private property and it is up to the home owner to replace these, not Irish Water.

Irish Water says it is ‘committed to working with customers to ensure the removal of lead pipes’ and is ‘engaged in a programme to replace all public side lead connections’.

As for chlorine, Irish Water says it is a ‘necessary disinfectant used worldwide’ which ‘plays an important role in protecting public health by killing harmful bacteria in our drinking water.

‘The level of chlorine in public water is carefully monitored and controlled to ensure it is maintained at levels that are not harmful to health,’ it adds.

‘If the taste or smell becomes significantly more noticeable than normal, customers should contact 1850 278 278 and we will ensure it is promptly investigated.’

The main objection people have to the residual chlorine left in our water supply is the taste. Some filters, such as the bottles sold by Black + Blum (from €22.50), contain ‘activated’ charcoal to draw chlorine out of the water, to improve 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 as the gas will dissipate on its own.

In some circumstances, using a water filter might even be detrimental to health.

The ZeroWater filter claims to remove fluoride completely, but dental associations warn that 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 with filter use as they need to be maintained properly, otherwise run the risk of becoming mouldy and that in turn could cause problems with the clean water you’re drinking.

Black + Blum recommends ‘reactivating’ 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 a day, as if left ‘for long periods, mould spores can form’. It adds: ‘The charcoal removes chlorine from drinking water, so you might notice [mould] forming quicker than normal.’

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