Bees actually need quite a bit of water, particularly in hot environments. However, they aren’t terribly discriminate about where they get it and can end drinking from treated swimming pools and bodies of water that are treated against pests. I built a pair of simple automatic waterers for my hives that gives them a fresh, reliable source nearby.
These work on a simple principle of fluid dynamics and atmospheric pressure. You probably saw some version of this in grade school science but if you need a refresher, here is a diagram. My version uses a plastic plant pot and a large planter sauce. Both are available from most hardware and garden stores.
The saucer should be larger than the TOP of the plastic planter pot, because the pot will be inverted. Also, the planter pot should NOT have holes for drainage at the bottom since it must be water/air tight for this to work.
Invert the pot (open side down) and place it in the saucer. The saucer’s lip should be above edge of the pot on all sides and leave room around all sides to form the “trough”. With the pot in position, mark the edge of the pot around it’s perimeter BELOW the edge of saucer lip. These will be your drainage holes. About four should be plenty. I made mine with a simple electric drill to avoid cracking/splitting the pot.
These measurements are from the pot and saucer I found, so your’s may vary. Larger pots and saucers mean less refilling but are also heavier and harder to manage, so the trade-off is up to you.
Next, fill the pot nearly full with water. Place the saucer over the top. While holding both firmly together, invert the entire thing. Water should immediately drain through the holes and start filling the sauce. This is the part where the pot NOT having drainage holes at is “bottom” is import. The pressure will equalize when the water fills the saucer up the level of the holes you made… and then it will stop!
As the water level drops from drinking and evaporation, the pot will act as as reservoir and automatically top the feeder off without any effort on your part.
Bees are terrible swimmers and often drown when they fall into deeper water, so I added clean gravel into the “trough” between the edge of the saucer and pot. This gives them plenty of places to land and hold on to as they drink. You can also use decorative stones, glass, etc and even paint your pot with safe paints if you want something more attractive.