For obvious reasons, Native American encampments were usually positioned within easy reach of water, if possible.  The young women and young boys of the lodge were given the responsibility of fetching water at whatever time it was needed.  They dipped or ladled water into a container where their horses and buffalo had not fouled the clean water.  The container was usually a skin bag formed from an buffalo or elk paunch or perhaps a brass trade bucket such as the one in this painting.  The people used, out of necessity, whatever product nature provided to make containers.  When they could get a brass trade bucket they did so.