How many glasses of water in a 500ml bottle

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It’s one of the simplest drinks on the planet, surrounded by an endless stream of complex myths and theories.

From the eight glasses a day rule to the much debated benefits of warm water and lemon, we’ve decided that enough is enough when it comes to the confusion surrounding H2O.

So we've knocked on the door of two medical experts, to ask them everything they know about water, the body and optimum hydration.

Here's what they had to say - sans marketing bumf.

Your day in glasses of water

Just like most scientific sources, our experts were divided on the exact number of glasses of water a person should drink each day. What they did agree on however, is that you should listen to thirst signals from your body, and keep your water intake steady.

Here's a suggested water timetable*, based on what our experts had to say.

Morning: Drink a glass of water to rehydrate your body after the hours you've spent asleep without taking on any fluids.

Mid-day: Keep a 500ml bottle (around two regular drinking glasses) on your desk or in your handbag and take regular sips through out the day. Aim to refill the bottle once, or to drink around four glasses of water through the day.

Evening: If you've been to the gym or done any exercise be sure to rehydrate by slowly sipping around 500mls of water. Don't glug it down in one go.

Before bed: Drink some water around an hour before you go to bed, to ensure that your body is hydrated while it repairs itself overnight, but your kidneys get to rest too.

How much water do we actually need to drink?

The eight glasses rule has been held up and ripped down by experts and health officials on either side of the fence for years.

Most recently, Aaron E. Carroll, a Professor of Pediatrics and leading researcher at Indiana University School of Medicine, has claimed the rule came from a misappropriation of 1945 Food and Nutrition Board recommendations.

Writing in the New York Times, he says that while the recommendation is indeed that people need the equivalent of eight glasses of water a day, the document's subsequent sentence, which read: "most of this quantity is contained in prepared foods", has been largely ignored.

He concludes that we just don't need to drink eight glasses, because our food already contains plenty of water.

We asked Dr Emma Derbyshire, Founder of Nutritional Insight and Adviser to the Natural Hydration Council, plus Dr Jayne Busby, a GP at Bupa’s new Health and Dental Centre in Canary Wharf (Crossrail Place), for their expert advice.

“Water makes up over half of our bodies and is essential for them to function," begins Dr Jayne Busby. "The amount we need varies from person to person depending on their age, the amount of exercise they do, the climate, and their diet.”

“As a basic rule of thumb you should aim for around eight to 10 glasses of fluid a day, and you can get this from water and other drinks, or from foods such as cucumber and lettuce.”

“My advice however, is to listen to your body, as thirst is a natural response to dehydration. Checking the colour of your urine is also important. Urine should be quite clear and light coloured – if it’s dark yellow and you are passing less than 7 times per day then you need to drink more.”

Dr Emma Derbyshire agrees.

“Like vitamins and minerals, our fluid requirements are individual and depend on factors such as body weight and size, physical activity and the temperature of our environment,” she explains.

“European guidelines recommend that women aim to drink about 1.5 litres of fluid a day and men about 2 litres (on top of water provided by food in our diet). This is about eight 200ml glasses for women and ten 200ml glasses for men.”

“Confusion around drinking eight glasses of water has come about as in the scientific community when we are talking about water we are referring to the ‘nutrient’ [rather than simply glasses to be drunk] – which is present in all fluids and foods.”

Is there a ‘best time’ to drink water?

Will two glasses of water in the morning really ‘wake up’ your internal organs?  Does a glass of water before and after every meal actually help with digestion?

There are plenty of myths out there about when and why to drink water, so we put a few of the most popular to our experts.

Does drinking water first thing in the morning help to ‘kick-start’ your internal organs?

Dr Busby: Drinking water in the morning is good for cleansing your system and kick-starting your metabolism.

 Dr Derbyshire: This is speculation only. That said, it is worth having a drink of water when you wake up to make sure you're starting the day hydrated, as most people wouldn't have had anything for quite a few hours.

Verdict: Our experts may not agree on the specific benefits, but both believe it's a good idea to hydrate your body with a glass of water on waking

Will drinking a glass of water before a meal help during digestion?

Dr Busby: Drinking water before a meal can curb hunger and encourage you to eat more slowly, it also helps your metabolism to swing into action.

Dr Derbyshire: The science supporting this as a digestion aid is weak, it is more about satiety and feeling full than digestion.

Verdict: Drinking water before a meal won’t necessarily help with digestion, but it might leave you feeling fuller.

Does drinking a glass of water before bed help to prevent stroke or heart attacks?

Dr Busby: It's a good idea to let the body and kidneys rest at night, so drink water up to one hour prior to going to bed.

Dr Derbyshire: This is a myth, there’s very little science to support the theory.

Verdict: Drinking water before bed won't combat the risk of stroke or heart attack.

Are there correct or best times to drink water during the day?

Dr Busby: I tell my patients to aim for one litre in the morning and one litre in afternoon. Bring a 500 ml water bottle to work and fill it up during the day. It’s always a good idea to drink 500 ml of water after exercise as well.

Dr Derbyshire: Your hydration status is constantly fluctuating throughout the day so it depends on what you are doing, the temperature and whether or not you are in a hot and dry environment (i.e. air conditioning or central heating dries out your environment). Most people don’t drink enough water however, 60% of people in the UK drink just one glass of water a day.

Verdict: Our experts didn't agree on a timetable per se, but both recommend drinking water regularly through out the day.

Is there a best 'type' of water to drink?

Celebrities far and wide – Jennifer Aniston, Beyonce and Gwyneth Paltrow to name drop– swear by the benefits of slurping their way through a glass of water and lemon every morning. Others meanwhile, claim that drinking tepid water is better for your body.

So is there really a best 'type' of water for us to drink?

“Still or sparkling plain water is best,” says Dr Derbyshire. “Water in tea or coffee counts towards your daily intake and hydration, although they are best to drink in moderation, especially if you're adding sugar to them.”

"A slice of lemon can encourage people to drink more water as they like the taste of it, however, citrus fruits can cause dental erosion because of their acidity. A slice of cucumber can be refreshing and also less acidic.”

What will drinking more water actually do for us?

It seems 'drink more water' is on the to-do list of women everywhere. Whether it’s in the pursuit of clearer skin and fewer wrinkles, or just to avoid the dreaded D-word (dehydration), there are even scores of specially made water bottles and flasks now being pushed at our plight.

But what does drinking more water – other than when you feel thirsty and are naturally prompted to take a sip – actually get us?

“There are plenty of benefits of drinking water, says Dr Busby. "It helps combat dizziness and tiredness, and helps your kidneys to flush out waste. Plus you’ll find you have clearer, brighter skin with reduced lines.”

Dr Derbyshire also notes the importance of water in maintaining good general health, from our dental hygiene and metabolism to a safe body weight.

Given that water contains no sugar or calories, she advises that it's the best way to stay hydrated while looking after your teeth, and won't contribute to the toxins we take in via sugary drinks and food.

*This is just a suggestion based on our interview, as the experts have advised you should drink water as and when you feel thirsty, and if you're unsure or are worried that you might be either dehydrated or drinking too much water, consult your GP.

Images: ThinkStock / Words: Amy Lewis