The first physical sign of dehydration, after a couple hours, is that June's fingers start to feel a little stiffer and more brittle and slightly crack and when moving them from the position they've been in. Toes, too, but June's wearing shoes.

"Wow, that actually sounds like a really important job," June says. Water is a pretty crucial part of life, after all. "What sort of training did you have to do to be good at that?"
It sounds pretty difficult, too, and that you'd need a lot of training. Which it sounds like Mei already has a lot of practice by now, having done a lot of planets.

June looks at the 'good view' point, and nods. Yeah, looks good.