Do you REALLY need an £80 smart bottle to tell you when to drink water?

Do you drink ‘plenty’ of water every day, as NHS guidelines suggest we all should? Or do you forget, and find it’s the end of the day and all you’ve consumed is coffee and tea?

If you are in the latter camp, you’re not alone. At least a third of Britons claim not to drink ANY plain water, on a daily basis, according to a recent survey.

Not a drop.

And one in five said they hadn’t had a glass of water for a whole week, preferring to drink squash and other beverages.

The body, as it is often stated, is mostly water. We need to keep hydrated for just about every bit of us to function. And without drinking water, we would die, probably within a few days.

Fortunately water isn’t in short supply for most Britons, so this isn’t often a worry.

However, if you’re concerned that you’re not hitting optimal hydration levels, then help may be at hand in the shape of ‘smart’ water bottles – sleek, reusable plastic or metal flasks fitted with sensors that, when paired with a smartphone application, reminds the user to take a drink.

Some set hydration targets while others emit sound alerts should the user fail to drink hourly.

One is even ‘self-cleaning’, containing UV lights in the lid that sterilise the inside of the flask every two hours.

But optimum hydration doesn’t come cheap as prices for these smart bottles can be as much as £95. According to some experts, drinking targets are relatively useless, so surely no one needs a pricey, digital device to tell them they’re thirsty… or do they?

Bottles can’t know how much you need 

So just how do these new devices work? One of the bestselling products, made by fitness-tracker company Bellabeat, uses an outer rubber sleeve fitted with invisible sensors to track the volume of water inside.

Shaking the bottle triggers the measurement sensors, which beam the reading back to a paired phone app. Users input personal details via the app such as level of exercise, height, weight, age and medical issues, and an algorithm computes a personalised ‘hydration target’ for each day. By looking at graphs on the app, drinkers know how much they need to drink before reaching their pre-programmed optimum level of hydration.

Many products on the market work in a similar way. The most sophisticated also connect to fitness trackers or smart watches.

So far, so clever. But according to dietician Frankie Phillips, it is almost impossible for digital devices to compute an individual’s hydration needs.

‘The amount of water each person needs to drink depends on countless factors,’ says Phillips, from the British Dietetic Association.

‘Important factors include the weather, air conditioning in a room, if you’re talking a lot, if you’re moving around, as well as many metabolic differences. You’d get a ball-park figure at best.’

The flawed evidence behind water targets

According to beauty devotees, drinking copious amounts of water is the secret to clear skin and peak health. Smart-flask manufacturers echo their logic, promising health benefits should drinkers imbibe between 500ml and 800ml of water daily. But where have such goals come from? Adequate water levels are essential for transporting nutrients around the body and removing waste products but according to many scientists, water-drinking goals are based on little more than ancient myth.

A 2002 review published in the American Journal Of Physiology highlighted a lack of evidence to support any water-intake rules. The scientists even argued that the eight glasses daily target touted by many health ‘gurus’, is based on flawed studies. Today, American guidelines set no specific recommendation for water or fluid intake. They simply advise people to drink when thirsty, and stick to low-calorie, low-sugar drinks. The NHS advises drinking between six and eight mugs of fluid everyday – roughly 1.5 litres. This doesn’t need to be water – juice, squash, low-fat milk, tea, coffee, soups and whole fruit and vegetables count.

If you forgot to drink, could you dehydrate?  

Should we fail to drink six to eight glasses daily, does disaster set in? Not so, according to Phillips. ‘Mild dehydration can cause temporary problems with concentration and sometimes headaches but most people will notice the colour of their urine is darker than usual, or feel thirsty, so will then drink something, easing the symptoms.’

As soon as the body detects dehydration, the brain initiates a thirst sensation. In healthy individuals, this causes them to reach for a drink. Simultaneously, a release of hormones signal to the kidneys to conserve water by concentrating the urine, delaying dangerous dehydration. ‘Most people drink what they need naturally because of our internal regulation system,’ explains Phillips. ‘Basically, drink when you feel thirsty.’

For the elderly there may be some benefit 

Scepticism aside, there is one group for whom smart water bottles may prove helpful. Dehydration among older adults, or those with impaired cognitive and memory function, is a widespread problem in the UK.

A recent report published by the British Geriatrics Society found that a fifth of 70-to-100-year-old care-home residents were seriously dehydrated. As we age, the water content in the body drops by 20 per cent. ‘Older people tend to go to the toilet more often and sensations such as thirst are less acute,’ explains Phillips. ‘Some avoid drinking during the day to stop them going to the toilet during the night.’

One recent study estimated that about five per cent of hospital admissions in elderly adults are caused by dehydration. And dementia patients are six times more likely to suffer dehydration than others. ‘For this cohort, anything that acts as a reminder to drink water would be helpful,’ says Phillips. But is an £80 chargeable bottle and smartphone application a practical solution to this problem?

Phillips says: ‘It’s not really practical for most people at this stage of life. But if written reminders aren’t working, it might be worth a try.’