For what I've read, do a 10:1 of water:bleach if you want to make sure you kill everything. But you MUST rinse and rinse and rinse and then rinse. Bleach can stay in the nooks and crannies of the lid, corners, etc pretty easily. Use a different towel every time you wipe it out too. I've also heard of people using vinegar. My mom's always used vinegar to clean kitchen counters and whatnot. It's safe to use, but, again, I'd still rinse and wipe it down pretty good afterwards.