Rain water ok to drink?

[BrittBergh]

I have a few rain barrels attached to down spouts of my house and was sitting here thinking of using the one closest to the chicken pen (its actually in their area) as their water. Was going to make an auto water system with either the cups or nipples. Wanted to know what thought about rain water as their water source is? Good? Bad?
I have plenty of barrels so having storage for the gardens wouldnt be too effected if one was for the flock.

 

[RJSchaefer]

As long as it's clean, I don't know why it wouldn't be. We're on a well, so all our water is technically rainwater.