we returned from a few days away to find the bodies of four fledgling bluetits drowned in a bucket of water - two of the bodies were saturated but two were floating - we removed the bodies and the bucket but later the parents came and perched nearby calling for the chicks - how do you think this tragedy occurred? before we went away, they were chirping quite happily in the nesting box on the end of our garage
I wonder if the poor little things tried to take a bath in the bucket, but because of the steep sides, they had nothing to stand on to give them traction to help raise their wings to get out. That's why bird baths are designed to be shallow with sloping sides, so that birds can bathe but also perch in the water, making it easy for them to launch off when they are finished. With relatively deep water in a bucket combined with almost vertical sides, it makes it almost impossible for the birds to get out.
When they are young their parents do everything for them, but they soon start to get them to do some things from themselves. I have experienced once a fledgling falling into deep water and unable to get out out. Luckily its mother was nearby and came and rescued it by swooping over and grabbing it whilst in flight. However, it is most likely that they were playing with each other and fell in whilst tryng to explore new things. But still remember that a deliberate human act is possible.