These are the 5 most (and 5 least) hydrating drinks to drink during the heatwave

Not all beverages were created equal. Here's what to chug for maximum hydration efficiency

Photos of water and a smoothie
(Image credit: engin akyurt / Douglas Bagg on Unsplash)

It's getting hot again, which means you might need to pay more attention to how much you're drinking, to ensure your body stays properly hydrated – especially if you're trying to do any kind of exercise in the heat. Water can get boring after a while, and while it might seem like almost any beverage should help, the truth is that some drinks are much more hydrating than others. (In fact, you can add foods into the mix; the most hydrating foods can be up to 96% water.)

Here, qualified nutritionist Abi Roberts (opens in new tab) shares the most hydrating drinks to drink in the hot weather, and the dehydrating ones that'll do you more harm than good (information via Forbes Advisor (opens in new tab)). 

5 most hydrating drinks

1. Water

Sorry to be predictable, but your best option is of course just water. "It is essential to our survival and is the absolute best choice to maintain hydration," says Abi. Here's our pick of the best water bottles to keep you topped up on the go, and the best water filters to pop in your fridge and make your tap water taste better.

2. Caffeine-free tea

Caffeine is dehydrating, as we'll get onto in the next section, but caffeine-free teas are a different beast – they can be almost as hydrating as plain water, and many contain powerful antioxidants too. Drink hot or cold. 

3. Low-fat milk

Low-fat milk is another excellent choice for hydration. "Milk is full of electrolytes which help to rehydrate the body after a bout of dehydration," says Abi.

4. Water infused with fruits or vegetables 

It's still water, but sticking some fruit or even vegetables in there can help jazz it up a bit on the flavour front, as well as adding extra vitamins and minerals. Abi's top suggestion is to add cucumber, which is one of the most hydrating foods you can eat (it's 96% water!). "Adding cucumber slices to your water boosts hydration even more whilst giving you the antioxidant properties and vitamins that cucumber contains," she explains.

5. Fruit juice

While they can be high in sugar, fruit juice still contains an average of 85% water, alongside health-boosting vitamins and minerals. Make sure you choose one labelled at '100% fruit juice' for the most hydrating effect, and beware smoothies, as we'll get on to next...

5 most dehydrating drinks

1. Alcohol 

Alcohol is dehydrating. "Alcohol removes water from the tissues in your body, which is why it’s common to feel like a shrivelled-up prune after a night of drinking," says Abi. The higher the alcohol content in the booze beverage, the more dehydrating the effect – so straight spirits (i.e. without a mixer) are the worst offenders, while something like a low-proof beer will be less so. Choose wisely for your pub garden jaunt. 

2. Caffeine 

Put down that iced latte: caffeine is naturally dehydrating, too. "High caffeine drinks (even when mixed with water) can end up dehydrating you or neutralising the hydration from the water content," explains Abi. Remember too that caffeine isn't just in tea and coffee; Fizzy drinks often contain caffeine too. These also often have a high sugar content, so overall they're just generally a horrible choice for staying hydrated. 

3. Smoothies

While we've established that many fruits and vegetables have high water content, smoothies actually aren’t great for hydration. "When you combine lots of fruit and veg and blend it, the sugars are released, which makes it far less hydrating," says Abi. "When the sugar is contained within the fruit or veg, it can digest through your body more slowly."

4. Energy drinks

If you're flagging in the heat, you might reach for an energy drink to give you a boost. Unfortunately, these are often packed with caffeine, combined with a lot of sugar. Long story short, they're not a good choice on the hydration front. 

5. Hot chocolate 

Probably not the beverage you'd naturally reach for during a heatwave, but hot chocolate is also pretty dehydrating. That's a result of the typically high sugar content, and it's even worse if high-fat milk has been added for flavour. "Opting for a low sugar and water-based hot chocolate makes it easier to stay hydrated," says Abi.

Ruth is currently on secondment as Sleep Editor for Tom's Guide and TechRadar. The role is an extension of her work on T3, where she ran the site's Wellness channel, which includes sleep, relaxation, yoga and general wellbeing. She was also Outdoors editor, reviewing and writing about everything from camping gear and hiking boots to mountain bikes, drones and paddle boards. She has tested more mattresses than her small flat can handle, and has had to implement a one-in-one-out pillow policy, for fear of getting smothered in the night.