I have a horse tank (warm all year round from sun or tank heater - it’s a floating heater plus I’ll be putting in something to float this year) nearby, a goose pond and several watering pails all very close. But then again we have animals on our 70 acres. I know in past years I’d find bees sitting around the water drinking and whenever I found one lost in the water I’d pull him out. I didn’t see those bees this last year though 
so I’m not sure what happened to them.
I should think of something to put in the watering pails in case the bees go there (guess some old barn wood would do).