Yes they do. A common cause of death in bees is dehydration. Bees can't use large expanses of water such as ponds as they can't swim same applies for bird baths. If you want to provide a water source for bees then use a shallow dish and fill with stones or small pebbles. The water will gather in the dish and the bee will be able to land on the stones / pebbles without the fear of drowning. We place many of these around our glasshouse and nursery and the bees love them.