We are having a problem in the pasture where we have our 6 horses. It is Someone elses land we are using free of charge. They are also letting someone else keep several bee boxes there and the bees are taking over the water supply. Can anyone tell me how to get them to leave the water alone without killing them or contaminating the horses?

what do you mean taking over the water? Like, the bees won't let the horses drink?

circlekinstructor, The bees stay on the tub most of the time. At times there are so many we are unable to switch the splitter lever to the hose for spraying the horses to cool them down. The horses normally go to the water, but there are times when they don't go all the way to drink...like they are checking out the area and find too many busy bees.

I'd ask the Beekeeper, they should know.
Could try adding another water source in a different location.
Good Luck