Providing water for honey bees can give you an opportunity to actively provide a needed resource for your bees and, if the location works out, a way to regularly observe your bees.
But, to understand the hows and whys of safely providing water for honey bees, we must first understand a couple of things about their biology.
Bees have three body parts: the head, the thorax, and the abdomen. All three pairs of legs, and both pairs of wings, are attached to the thorax. So, all of their locomotion muscles - for both flying and walking - are located in their thorax. In order for those muscles to work, the thorax must be at a minimum temperature of 85° F (some research findings vary slightly from this). Honey bees are not true ectotherms (animals that are completely dependent on external sources of body heat); they have several mechanisms for regulating their own body temperature. But, there are limits to that.
Another aspect of their biology that we must understand is how they transport liquids (water, nectar, and honey). They have a special organ called the "honey crop," among other names. They use their tube-like tongue, called a proboscis, to draw up liquids and store them for transportation in their honey crop.
(By the way, honey is NOT "bee vomit." Nectar and honey are never regurgitated from their actual digestive stomach. They are transported in the honey crop.)
If the liquid that a honey bee draws up is cold, it will lower the temperature of her body, including her thorax. If the muscles in her thorax are cooled to below 85° F, then the she must wait until those muscles warm back up before she can fly.
Another thing to note is that, if a honey bee gets blown into a water source by a sudden gust of wind, she will turn on her back and use her wings as high-speed paddles until she encounters a surface on which she can crawl out of the water. But, if the water is cold and her wing muscles stop working, she will not be able to "paddle" and will drown. So, you can imagine the challenges the bees face if it's cool, cloudy, breezy, and the water is also cold and deep.
Finally, we need to understand that honey bees do not like to forage close to their hive. It is their instinct to keep their hive location secret from other colonies so that they are not overwhelmed and robbed-out by a stronger colony. Given this instinct, bees will probably not use a water source that is within 50 feet of their hive.
So, understanding these things, how do we provide a safe water source for honey bees?
The ideal water source container would provide warm water, a shallow angle of entry, rough surfaces for the bees to cling to if it's windy, and a lot of surfaces they can quickly get to if they get blown into the water and have to paddle to get out.
Here's what I provide:
This is a bird bath in my back yard, and it provides all of the characteristics of a water source I just described. It is in the full sun all day, so the water stays as warm as possible, the angle of entry is shallow, the surfaces are rough, and there a lots of rocks close together for them to paddle to if they get blown into the water by a sudden gust of wind. In addition, it is more than 50' from the closest hive.
But, before you begin providing a source of water for your honey bees, here are a couple of things to think about:
Consideration number one: For myself, in order to provide this water source for my honey bees, I have to be willing to siphon the water out at night (so it doesn't freeze or get too cold overnight) and then re-fill the bird bath with warm water once the bees start flying the next morning. If I just leave water in it all the time, the first bees to fly to it each morning will cool down too much to fly home. I will find drowned bees in the bird bath mid-morning if I leave the water in all night.
And, consideration number two: Keep in mind, if you take time off, and there are a few days when you're not providing water at the source you've established, the bees will find another source and may not come back... even after you begin providing water there again.
Having mentioned these two considerations, I do encourage you to provide a safe source of water for your bees. If you can find a location that provides the characteristics I've mentioned above, and also provides you with a vantage point from which to observe them coming and going, fantastic! I love sitting in a chair about 12 feet away, out of their flight line, and watching them come and go in the late afternoon sunlight.
The fact that the water source actually needs to be more than 50' from their hive means that you might be able to find a sunny spot on your patio or deck and provide a water source there that you can readily observe.