I too have wondered at the bees interest in "dirty water."  For many years I kept
bees next to my horse barn and... especially in the spring (there may be
something to that)... the bees would seem to have a great interest in the thawing
manure pile.  I assumed they were acquiring water, but less tasty water was
available.  Perhaps in the spring there is a need in the hive for minerals not
needed during other seasons.

Larry Krengel
Marengo, IL