When it comes to trying to find out how much water we should drink in a day it's hard to know which advice to believe. There’s a lot of different guidance and information out there. Sometimes the answers lead to more questions, everything from "Is this in addition to other food and drink?" to “How much is a glassful?"
So, we've scoured the web and collated five approaches for you to look over so you can decide which suits you best and help you answer the common question: how much water should I drink a day?
1 - 6 to 8 glasses a day
The NHS takes their guidance from the UK government’s Eatwell Guide, which is a policy tool used to define recommendations on eating healthily and achieving a balanced diet. The guide advises we all should drink six to eight cups or glasses of water a day to replace normal water loss. That’s around 1.2 to 1.5 litres a day. In hot weather or if exercising, then we should drink more.
Water, low-fat milk and low-sugar or sugar-free drinks, including tea and coffee, all count towards our daily recommended fluid intake. But fruit juice and smoothies contain ‘free sugars’ that are released when fruit and veg are juiced or blended. They can damage our teeth, so we should drink no more than 150ml a day. That’s about one small glass.
Fizzy drinks, flavoured waters, squashes with added sugar, energy drinks and flavoured milk drinks all contain lots of sugar so we should avoid these. Also beware of caffeine - it’s a stimulant that can affect some people more than others and it can also make you produce urine more often. Tea or coffee are fine as part of a healthy balanced diet.
2 - 2.5 – 3 litres a day
So say the World Health Organization, but they do caveat this with ‘depending on environmental conditions’ and ‘under normal circumstances’.
But what’s ‘normal’? What ‘conditions’? Obviously, this is a valiant catch-all attempt at giving every single person around the world one sound bit of clear, sensible advice. The trouble is that we're all different shapes and sizes, we all live different lifestyles in different parts of the world – can it really be the same for all of us? Should everyone all be drinking the same amount of water a day? Is there a limit to how much?
3 - 1.6 litres a day for women, 2 litres a day for men
The European Food Safety Authority sets a more conservative recommendation that’s significantly less than that suggested by the World Health Organization. And, assuming all men are bigger than all women, they differentiate between how much water a man needs to drink and how much water a woman needs to drink a day.
4 - The 8x8 rule
This is effectively the same as the 2.5-3 litres recommendation. But while investigating this for the BBC, Dr Chris Van Tulleken realised that supposedly scientific literature supporting this rule was, in fact, more marketing than research - the article was supported by a manufacturer of mineral water. Further to this, Heinz Valtin, MD tried to debunk this idea back in 2002 when he found no scientific evidence to support the 8x8 rule.
5 - Only when I'm thirsty
Not to worry you or anything, but if you're feeling thirsty this could mean that it's too late - you've already become mildly dehydrated. The trick is: don't get dehydrated. It's not good for you. Simple.
One way to tell if your body needs water is the colour and smell of your pee.
- Clear urine with no smell = well hydrated
- Dark yellow to orangey/brown and smelly = dehydrated
Waiting until you're thirsty is not the best rule to follow, neither is waiting until you've got smelly brown pee. Your objective is to always have lovely clear, odour-free pee.
So, how much water should you be drinking a day?
Obviously by now we've realised there isn't a simple, straightforward answer for all. It's the old 'it depends' scenario. According to Dr Chris Van Tulleken, “you don't need to worry about exactly what that total daily requirement is because your body will sort it all out for you. If you drink too much you pee it out. If you drink too little you get thirsty and pee less. It's all exquisitely well-controlled.”
But does this 'not too little, not too much' approach give us complete confidence? Or have we developed an unhealthy dependency for an 'expert' to prescribe exactly what to do and not trust our own bodies?
Ultimately, we have to listen to what our bodies tell us and use a little common sense to work out our own personal hydration needs based on gender, age, height, weight, geographical factors (temperature, altitude, humidity), sleep schedule, diet, types of beverages we consume, as well as activity and exercise patterns, all these things will help you determine how many litres of water should you drink a day.
So, the answer is that there is no real answer: it's different for everyone and we need to work out what is best for us.
How much water should children drink a day?
The UK Eatwell Guide doesn’t suggest children should drink any less than the general 6 to 8 glasses a day rule. It recommends that between the ages of 2 and 5, children should gradually move to eating and drinking the same stuff as the rest of the family - providing they’re following the healthy Eatwell rules, that is.
However, the European Food Safety Authority is more specific. It suggests that:
- 1.1-1.3 litres per day for boys and girls aged 4 to 8
- 1.3-.5 litres per day for girls aged 9 to 13
- 1.5-1.7 litres per day for boys aged 9 to 13
What can be agreed on is that water and milk are the best drinks to give kids, and fizzy, squash and juice drinks should be completely avoided as they contain lots of sugar.
Can you drink too much water in a day?
The ideal method of fluid intake is to sip often throughout the day, rather than gulping down huge amounts at one time. Drinking too much water too quickly could cause you problems. Over-hydration means your body isn’t able to do its processing job properly, your body can cope with a litre of water an hour at the most. Logic would dictate that you should not be consuming more than that in one sitting.
What are the benefits of staying hydrated?
There are many benefits of staying hydrated and making sure you consume enough water, in the right way. Aside from the obvious benefits of improving digestion and avoiding headaches, water also keeps you in a good mood, improves digestion and helps prevent illness. Always make sure you know how many glasses of water a day to have, and your body will thank you for it. Here are eight great reasons to drink more water.
