Imagine just one bee work for a day, attending to least 2,000 flowers a day, beating their wing 10,000 time per minute, carry baggage of pollen, go back in their hive, go to their selected comb making honey with their spit, pollen, and wax. And go out again everyday.
Sounds exhausting? Bee does get thirsty, and they do need water source, they tend to find the nearest water source like many of us look for water fountain in the park if you don't have water bottle handy. The problem is water is not always available, sometime with luck bees will find puddle of water from recent sprinkler activity or spilled juice on the ground.
At the best, the bees need very shallow water to drink from, but Shallow water evaporate quickly. Birdbath is not a good option because bird can be nearby and they tend to drown since it may not be shallow enough and simple wind gush can push enough to land into water. For bees with pollen on them is like people swimming with clothes on, an difficult task, and often can result in drowning. As for river and lakes, they risk their live hanging on the plant trying to get sip of water in front of fishes, frog, and risk being swept away in water current.
This instruction is very easy, and only require 3 items, this will give plenty of water, and safe place to land on and off without problem.