The pitfall trap with water at the bottom seems like a good idea. The mouse isn't going to drown if you check the trap in the morning after you wake up.I'm not dead set against killing the mouse. I've had to euthenase injured animals before (e.g. fish that got cancer and started swimming on their side, birds which were mauled by family cats). But you aren't really fixing anything by killing one single mouse. It's not like all the disease is going to go away just because you kill one mouse.
Anyway, there are articles on the internets with various opinions on how to humanely kill a mouse. Spring traps and molten lava are not among them.
You'd think so, but due to small lung capacity and not being designed for swimming, after a couple hours they'll be dead. If you want to be more humane I hear putting bleach in the water will kill them faster. It still sucks for the mouse but at least they die fast instead of slow.
If you're going to get them it usually happens shortly after you go to bed/turn the lights off, so unless you get a mouse that can tread water for 6 hours, it's pretty boned.
Hmm, good thinking, I guess its unlikely to be able to tread water for long. Best bet would be to use a large bucket so it cant jump out. I would still want to avoid causing it any unnecessary suffering. Adding bleach to the water isn't going to make this any better; i would rather drown for 6 hours than go blind and choke on my own blood for 2 hours. Chances are, whoever has used bleach in this way didnt notice the water being full of blood because of the bleach.