Put something in the water container besides just water. Some things that may be suitable include sponges, wood chips, small rocks, cloth, etc. The bees need something to stand on. You could also, if you have room in the "pavilion", use something like a boardman feeder, with just water in it.
A very simple boardman feeder can be made by punching small holes in the screw-on lid of a glass jar, and inverting it onto some shims big enough for the bees to get to the holes in the lid of the upside-down jar.
-- Victor Hugo -- "Common sense is in spite of, not the result of, education.”