So, just to recap: forty kids, who were ostensibly being cut loose to build a society on their own terms, are now about to have adults provide them with an arbitrarily determined social structure, an artificial economy, and fully-stocked stores in addition to the huge loads of provisions they've already been given. So clearly this is not going to be as Lord of the Flies as we've been led to believe. I'm not saying this is a bad thing; just don't promise us Lord of the Flies and then give us Endurance.
The kids all go to their bunkhouses to change into their uniforms, which are simply different colored t-shirts with "BONANZA CITY" and their names printed across the front. Greg is confident that Blue has an advantage, with bigger and older kids like himself. He and Blaine run around the town, chanting "Blue" at everyone and writing "BIVE" all over everything and generally making azure-tinted nuisances of themselves. Greg starts to tag the sign over the Green bunkhouse, until Jimmy chases him away, shrieking in tiny berserker rage. No wingman for you! Mike and Jared come up behind Greg and some other Blues hollering, "Red! Red! Red!" until the bigger kids chase them off. Yes, Mike showed them, all right.
The showdown is a Survivor-type challenge set up in a field outside of town. There are four big color-coded pumps, each a different-colored metal assemblage about twenty feet high. There are also four racks of three large bottles each, also representing each District's color. Jonathan explains the object of the showdown: each team will have to physically move its pump out into the field, connect it to various pipes sticking out of the ground, and pump out water that's dyed the color of their District, which they will then catch in buckets and use to fill their bottles. Jonathan hands out maps of the pipes in the field to the Council members, and explains that each District's caste (he doesn't use that word, but I mean, come on) will be determined by the order in which they fill their bottles. And if all the teams finish in an hour, they get a mystery reward for the whole town. He points over towards a couple of big crates, and the kids all "ooh" obligingly, even though nobody knows what's in them.