Guzzling water has become something of a badge of honour among celebrities, with Jennifer Aniston and Gwyneth Paltrow revealing they drink up to three litres a day. But not everyone finds it so easy. Florence Pugh, for one, recently announced that she finds water “too boring to drink”. As well as the lack of flavour, she bemoaned the constant toilet breaks that come with a high intake, calling them “a waste of time”. Instead, she prefers orange juice, elderflower presses and tea.

What do the experts say? How much water should we be drinking every day – and is it just as healthy to get your hydration from other beverages?

Chester-based GP Chris Ritchieson says NHS guidelines suggest drinking around six to eight glasses of water a day, which is roughly two litres. “Although this is the general guidance, there is very little concrete research and evidence about the optimum amount of water to drink,” he says. “People have different sensitivity levels to dehydration, so it could vary from person to person.”

When dehydration symptoms do occur, they can be hard to spot, and easily confused with something else. “Not drinking enough can increase the risk of urinary tract infections and headaches, along with tiredness, confusion, passing darker urine, dry cracked skin and irregular bowel movements,” says Ritchieson. It can also lead to low blood pressure or postural hypotension, a condition where standing up can cause sudden dizziness and falls.

Drinking more water, meanwhile, can help to prevent health conditions such as migraines, frequent headaches and kidney stones.

While plain water is the healthiest source of hydration, Ritchieson says any non-alcoholic drink makes a contribution. When, in 2016, researchers at the University of Stirling monitored hydration levels in students for four hours after taking on different liquids, they found that a litre of instant coffee – and even beer – was as hydrating as the same amount of water. But hydration levels remained highest of all, above water even, after drinking milk.

Although this is the general guidance, there is very little concrete research and evidence about the optimum amount of water to drink. But it’s not a good idea to drink many water alternatives on a regular basis. “Tea and coffee are diuretics, which means they make you go to the toilet more often,” says Ritchieson. “Fizzy drinks, squashes and juices will also hydrate you, but we discourage people from drinking too much due to the high sugar content, which can lead to other health issues in the long-term.”

The caffeine in tea and coffee can cause other side-effects, according to Nishtha Patel, a functional medicine practitioner and clinical nutritionist. These include an increased heart rate and palpitations, anxiety, restlessness, insomnia, digestive problems such as nausea and diarrhoea, sleep disturbances, high blood pressure and even caffeine addiction. “It is recommended that we limit caffeine intake to about 400mg a day, which is equivalent to approximately four to five cups of coffee or eight to 10 cups of tea,” she says.

When it comes to sugar, the NHS recommends consuming no more than 30g of “free sugars” a day, which includes sugars added by food manufacturers, as well as natural sugars in fruit juice, honey and syrups. Patel says that some fizzy drinks or energy drinks contain enough sugar to take us over the daily recommended intake in just one serving. “Diet drinks are really not much better. They affect the gut microbiome and, like other ultra-processed foods, have been linked to other diseases, including memory decline and liver issues.”

Fresh juices contain more nutrients than fizzy drinks, but Patel warns it can still be easy to go over the recommended daily sugar allowance. “On average, a (225g) serving of freshly squeezed orange juice contains around 20-25g of sugar. Consuming too much sugar, even from natural sources, can still have negative health effects and increase the risk of type 2 diabetes and obesity. Water hydrates us with zero calories.”

If, like Pugh, you find drinking water “too boring” or tasteless, the nutritional therapist Thalia Pellegrini recommends adding fruit or cucumber to a water jug and putting it in the fridge. “That adds just enough flavour for some people,” she says. “You can also try herbal teas and diluted fresh juices. If you really can’t stand the taste of water, try adding squash. It does have a lot of sugar but it’s better for you than going without fluids.”

A diet with plenty of plants can help, as you’ll get extra hydration from fruits and vegetables. “Some ingredients like celery, lettuce, tomatoes and watermelon are more than 90% water,” she says. “You can also try eating plenty of peaches, pineapples, oranges and pears.”

And what about the people who avoid drinking water because they are afraid of needing the toilet too often? Veerpal Sandhu, an advanced clinical pharmacist for GP surgeries in Essex, says this is especially common in pregnant women and elderly people, who may have more issues controlling their bladder. “Mostly people manage by not drinking too much before travelling, going out or going to bed,” she says. “One solution is to drink more when you are near available toilets. And there are pelvic floor exercises you can do to improve bladder control.”

Ritchieson adds that for older people, restricting fluid can lead to more toilet breaks. “It makes the bladder more sensitive, so they actually need to go more,” he says. “We tend to find that a lot of people, especially in the summer months, underestimate how much they need to drink.”

Sandhu points out that water is essential for human health. “It makes up over two-thirds of the healthy human body. It lubricates the joints and eyes, aids digestion, flushes out waste and toxins, and keeps the skin healthy.”

It is, of course, possible to drink too much water. “As a result of some of the publicity – often from celebrities – about drinking more, we occasionally see people who have become unwell from drinking too much,” says Ritchieson.

“Overhydrating can lead to a condition called hyponatremia, which means that your salt levels have become too diluted. This can cause headaches, dizziness and, in extreme cases, unconsciousness. If you’re going to increase your water intake, I recommend doing it gradually and drinking little and often throughout the day.”

How much is too much will depend on the individual, and how fast they are drinking. “That’s why we always recommend little and often,” says Ritchieson. “The kidneys can eliminate 20 to 28 litres of water a day, but no more than about a litre an hour, so the important thing is to spread your intake out throughout the day.

“For most people, unless they are exercising, living in a hot climate or unwell, about 1.5 to three litres of water a day will always be enough.”