No Expert - but........
When I worked for HM Queen I did a bit on desert survival etc. which, of course, has a lot to do with dehydration and how to avoid it.
Salient points that I remember were that up to 90% of the water content of juice, (especially cordial but not exclusively), would be required by the body to process the sugar, (natural or otherwise), contained in the juice, leaving only 10% to cope with re-hydration.
If one is about to embark on a period where dehydration is likely, (a long flight, for example), simply sipping at water throughout the period isn't good enough.
Far better to thoroughly fill your body with water first, drink 2 to 3 litres before you start, take your body way, way above the point at which dehydration begins and then it will sink towards the dehydration threshold, all this time you are physically and mentally capable. At the first signs of thirst repeat the process.
If you simply sip at water you are going from just above to just below an acceptable level of hydration, continuously, and are continuously likely to be below par both mentally and physically.
So, sipping on its own is not good enough.
It is important to be able to recognise the symptoms of the onset of dehydration. By the time you feel light headed or your joints ache, concentration is drifting away etc. etc. it is TOO LATE, you are now considerably dehydrated. Thirst is a good pointer.
Additionally, if you notice that your urine is darker than usual and smelly then you are dehydrated.
From an aviation point of view avoiding dehydration should be quite simple, top up with water well above the 'norm' before you go and maintain a high level of hydration as you go.
Always drink water in preference to other drinks if it is available.
Ensure your company policy is to make available sufficient drinking water for the crew.
Last edited by BlueEagle; 29th July 2002 at 10:23.