Honey bees need water (for drinking, but also to evaporate in the hive to cool it), so providing a nearby source will help them and avoid unexpected reactions from crowds of bees drinking the water from the edge of your neighbours pool or bird bath.
Despite our best intentions, bees will often drink from alternate dirty water sources in preference to the pristine and pretty sources we provide! In this photo you can see that despite a nearby pond (created explicitly for their use), they'd rather drink the rainwater pooling in a tarp, covered in mud!
If you do create a dish to collect rainwater, make sure you have a gently shelved edge so they can walk down to it without drowning, or place rocks in it so they can land safely. If they do land in the water, having rocks or some floating material allows them to climb out again easily. Some people put sponge in the water so the water is wicked up and the bees have no chance of ever drowning.
