Here was my problem: the pigs, who are right outside my office window, were constantly sticking their muddy hooves into the water bucket and dumping it over. I would watch, yell at them sometimes, and then end up going down to fill it up again. The book was never going to get done. In addition, the ground is so gravelly that the water we hosed in their yard to give them some relief from the (albeit very short) summer sun disappeared so fast that they barely got to take advantage of it.
Then I remembered the old kiddie pool that we picked up off the side of the road last year, ostensibly for Laika, who decided that although she has webbed feet, she really doesn't like getting wet all that much.
I pulled the pool into the pigpen. At first, the pigs only sniffed at it. But a few hours later, I caught them trying it out. They're frankly a bit unwieldy (ok, fat!) and they don't like the slide at all. But they've gotten the hang of it pretty quickly... they climb in and out, they cool themselves off, they wallow.
Not only that, but their water bucket stays clean and upright.