On our camel safari from Jaiselmer in Rajasthan, India we stopped a couple of times for the camels to fill up on water. That's Cindy in her orange turban. When we arrived the trough was already filled. After the camels had their fill we had to fill up the trough by pulling a rope attached to a bucket that went a good 100 feet down. With of us pulling, tt took about 15 pulls of the bucket to fill up the trough.
The idea is that if you happen to arrive at the well in desperate need of water you have water immediately available. This could save your life.