How can a toddler drown in a bucket of water?

Physics. The more common offender is the 5 gallon paint bucket or similar, but a toilet had worked the same on occasion. Kids are top heavy.If they bend over and flip in their body weight pushes them down and they no leverage to back out.If there is no one around to pull them out they drown.
Easily. The water only need cover nose and mouth. People have drowned in an inch of water.