As the person running waterbearing for Autumn War 2011 (3D), I would like all advice regarding to or involved in waterbearing.
I need info on where you get your waterbearing supplies, the kinds of people you get to volunteer, how to tell who is the most dehydrated, when to notify a medic, when to sploosh a fighter with water (no, not just because they're naked from the waist down ;P) etc.
One thing that I've found that is much appreciated in hot weather: I carry two jugs. One for drinking and the other with half of the top cut off. We put a wash cloth in that one and fighters can wring cool water out over their heads, necks, etc.
Otherwise, in this area, we often use gallon water jugs and clean fish tank tubing. The tubing can be run down the handle of the jug to keep it in place, but can also be cut long enough that the fighters can get a drink without removing their helms.
I noticed that nobody else has responded to your question. Did you get the infor you were looking for?
To address the questions taht I didn't answer before:
"the kinds of people you get to volunteer" - anybody willing to haul a jug of water around. If it's a large/busy list field, I would hesitate to allow children to volunteer because of the safety issues involved (will they indeed stay off the field, etc.).
"how to tell who is the most dehydrated" - you don't need to. As waterbearer, your job is to offer water to whoever will take it. It's up to the marshallate and chirurgeonate to determine that somebody is unwell. You can help by mentioning any concerns you may have to somebody (out of respect, mention them to the fighter first - he or she may be able to alleve your worries).
"when to notify a medic" - if you see somebody who is unsteady on their feet, incoherent in their speech, or otherwise appears unwell, then ask them if they are okay and tell them what you are seeing that is causing you to be concerned. If you notice that somebody refuses all offers of water, mention it to them (they may have their own supply). Most people will "police" themselves. However, if you mention your concerns and they are not able to reassure you that they are fine, then quietly point the person out to the nearest marshal or chirurgeon and tell them why you're concerned. After that, it's in their hands and not your concern any longer - unless asked to keep an eye on the person or something, do not keep pestering the person, you'll only upset people.
"when to sploosh a fighter with water" - only if they ask you to. This is where a bucket with a wash cloth or small water scoop comes in handy - you can offer it to them and whether or not to use it is up to them.