The idea is that there's this here heat wave, so this owner of a bottled-water company who talks like a game-show host, Bud Flud, decides that the only logical step is to poison all the other brands of water so that people will have no choice but to buy his stuff--though I'd think the real competitor, which he doesn't do anything with, would be tap water. What I like about ol' Bud is that he has these giant-water-bottles-with-women's-legs following him about singing jingles, like those terrifying giant packs of cigarettes in those old commercials. And when he's poisoning the water, he's accompanied by poison-water bottles, as why the heck wouldn't he be?
So Darkwing catches him in the act, and he falls in a tank of poisoned water (which seems to have become some sort of corrosive, acid-like thing) and dies. It's quite gruesome for a show like this, really. "All the better!" Darkwing cheerfully remarks, "cases are so much easier when the bad guy offs himself like that!" This strikes me as awfully callous.
Anyway, big surprise, he's not dead for good--he returns as a guy made of water. Also, he can psychically control water apparently, though this isn't exactly spelt out. And he's changed his name to Liquidator, which seems like it would be bad for brand-recognition, given that he's still trying to sell water, albeit in a rather more coercive manner. Ultimately, he makes all the water hard (and yellow, for some reason) so he can charge people for the regular kind. But Darkwing foils him by pouring cement on him and making him into a statue, which is also rather more unpleasant than the fates most villains meet.
As I said, what I really like about Liquidator is the rotating cast of women in appropriate costumes that he has singing fifties-style jingles for him. That's funny. But I'm kind of assuming he won't have those in future episodes, which…well, we'll see if they can give him something else to make him stand out.
-There's a great part where the bay is turning hard, and a fish is stuck on the surface and baffled by the proceedings. Later, we see the same fish who, having decided to turn lemons into lemonade, is sitting on the water with an umbrella, shades, and a fruity drink. That's my kinda fish.