It's a lot less cruel than those awful sticky goo traps or even spring traps, for that matter. My roomies and me came up with the toilet trick for that reason; watching a rat struggle in agony because it's spine was snapped, not it's neck, or seeing a little mouse all stretched out and contorted, squeaking in fear and pain, from struggling against the sticky goo really makes drowning seem the better alternative. And yes, unless the rat is quite large, it can be flushed. They're sleek and elongated, normally.
