@CodexofRome: Do you talk about the water situation after that first session?
Yes, oh yes. For two reasons. First, fresh water is so vital to life, it has to be a constant concern for anyone not blessed with plenty of it. Second, but equally important, the details we forged originally about water became fundamentals of the story, and vectors for threats.
My players had decided they'd catch rainfall during the rainy season and store it in boilers and vats that had been liberated from nearby breweries and industries. For the dry season, they had a well that had been drilled down to the aquifer. It was established that people living in Tabernacle would come in the morning to get their draw of well water, and that's where the next couple of sessions would begin, in the morning, watching over the water distribution.
Two threats involving water got more play than almost anything else.
The first was an environmental threat, a large marsh that even in the dry season never quite dried up. The marsh is a couple of miles from Tabernacle, situated in between the site of a small nuclear reactor at a research university and the headquarters of what had been the world's most popular soft-drink. To me, that added up to a big soup of chemicals and mutated bacteria, something that could be a big problem if it got into the aquifer.
[We're playing in our own backyards, in Atlanta, so this is the Coke HQ and the reactor at Georgia Tech. The real reactor in question, was actually shut down and de-fueled before the 96 Olympics. And two of the players work at the Coke HQ in RL.]
The second threat was from the primary front, the enemy at Big Rock. Barnabas sent his reclusive brainer, Zip Gorgeous to infiltrate Tabernacle. Zip sold himself as a chemist who could help them create explosives, something they ate up like candy. They sent him out, along with Flint, one of the Chopper's gang, for protection, to get the supplies he needed. Zip puppet-stringed Flint, who was caught red-handed (having been puppet-stringed) poisoning Junktown's well. That put an end to alliance talks.