Do you need electrolytes? Will tea cool you down? Is it safe to drink beer? How to stay hydrated in a heatwave

The hotter it gets, the faster our bodies lose water. Obviously, we need to replace it – but is anything better than plain H₂O? And does timing matter? Here’s what the science says Hydration is important. In temperatures like those we’re increasingly seeing in much of the world, sweating can be the only way for our bodies to cool down, and our thirst isn’t always the best indicator of how much water we’ve lost or need. The consequences of not being sufficiently hydrated as temperatures creep towards the 40s can be severe, and can kick in much faster than most people realise. The good news is that remembering to drink plenty of water at regular intervals throughout the day will be enough for most people to avoid the worst. But if you’d like to understand why dehydration is so dangerous, whether you really need extra electrolytes, or if a cup of tea really can cool you down, read on. To start with, it’s helpful to understand that our bodies are producing heat – and therefore losing water – all the time. “All the cells in our body are constantly using fuel for energy for various different processes, whether that’s movement or just staying alive,” says Dr Lewis James, a lecturer in spo