Water makes up two thirds of the human body. As such a large component of our physiology, staying hydrated is a key element of maintaining day-to-day health and ensuring people avoid more serious problems like chronic headaches, constipation, dizziness, urinary tract infections and kidney stones, says the NHS.
Anyone can become dehydrated without replacing fluids lost in the body through urination, breathing and sweating (it is estimated just a one to two per cent drop is noticeable), but those particularly at risk are babies, the elderly, those with long-term health conditions and athletes.
Signs of dehydration are often most visible when you pass urine. Dark or strong smelling wee is an obvious sign you need to be taking in more fluid. As well as this, pain when weeing, a dry mouth or lips, thirst, tiredness and lack of concentration can all be attributed to dehydration.
If dehydration is left untreated it can become a medical emergency which requires attention. Symptoms of severe dehydration include a weak pulse, rapid pulse, not passing urine for more than eight hours and fits or seizures. This can be life threatening in older people.
So just how much should you be drinking? And what can be done if you struggle to remember?
How much should I be drinking?
The NHS Eatwell Guide still recommends adults in the UK drink between six and eight glasses of fluid every day, this should equal around 1.2 litres (and more when the weather is hotter), although will obviously vary depending on the size of your glass. These glasses should be paced equally throughout the day, rather than consumed all at once.
The “six to eight glasses” figure was first suggested in a 1945 US Food and Nutrition Board Council paper as well as in a hugely influential Nutrition For Good Health book, written in 1974. Even Michelle Obama was encouraging people to “Drink It Up” in a 2013 campaign to get Americans drinking more of the good stuff.
But much of the narrative now overlooks that in those early recommendations they said that not all of that needed to come from water, or even liquid, with some being in your food (fruits and vegetables can be up to 98 per cent H2O).
So how much should you be drinking now and where can you get it from?
Does it just have to be water?
Many people now carry reusable water bottles - with workplaces encouraging their use and (pre-coronavirus) businesses were starting to allow customers free refills rather than always buying bottled water. But carrying a bottle doesn’t always mean you drink it.
The Eatwell Guide says ideally people should “drink plenty of water” as the primary way to hydrate. “Water is a healthy and cheap choice for quenching your thirst at any time. It has no calories and contains no sugars that can damage teeth,” it says. It recommends if you do not like the taste of plain water, try sparkling or add a slice of lemon or lime to your beverage.
But if you are someone who regularly forgets to drink water, there are other drinks that count towards your daily target so don’t be disheartened.
In fact a 2015 study in the American Journal of Clinical Nutrition, looked at the short-term hydration effects of a dozen different options and found (based on urine analyses of participants) that milk, tea, and orange juice, but not sports drinks—were more hydrating than plain water.
But the benefit of water over other drinks is that it doesn’t contain hidden sugars, which can be damaging to your teeth, or additional calories.
Does tea and coffee count?
The NHS says plain tea, fruit tea and coffee are also ways of getting more fluid without necessarily having something high in fat or sugar. Bear in mind though that caffeine does make the body produce urine more quickly as it is a diuretic, so you might need to replace lost fluids more often.
And if you have added milks and sugars in your coffee or tea, or syrups in flavoured drinks, then they are also containing hidden sugars and calories that water does not.
Does food count?
Linda Antwi-Ahima, a pharmacist at the Peninsula NHS Treatment Centre, says: “You don’t need to rely only on what you drink to meet your fluid needs.
“What you eat also provides a significant portion. For example, many fruits and vegetables, such as watermelon and spinach, are almost 100 per cent water by weight.”
How can I remember to drink more?
If you’re still struggling to remember to drink any liquids throughout the day and worried you’re regularly dehydrated, the NHS recommends the following ways of gradually increasing your consumption.
Adding fruit or herbs to plain water can make it more appealing; keeping it cold so it tastes more refreshing than water at room temperature, filling a one litre bottle and aiming to drink it throughout the day, drinking a glass of water with every meal, and asking for a jug of water when eating out of the house at restaurants.
You can also download apps that remind you to drink water at regular intervals throughout the day or buy bottles with time slots marked on the side. There are a number of apps that also allow you to set daily goals so you can increase your intake over a period of time.