Superhydrate me. I need to drink water. Litres of it. Otherwise, how can I stave off dehydration? Then, my heart would labour to pump “thicker” blood. My concentration might “nose dive”, and I could crash my car. So superhydrate me now.

I have been reading the website of the Natural Hydration Council, a body that says it is guided by a panel of scientists. My layman’s precis of its “top ten tips for healthy hydration” is as follows: we need up to three litres of fluid a day; dehydration is dangerous and occurs before we feel thirsty; drinking water regularly is the best way to avoid it.