Based on these two photos and the accompanying text images, here is my best guess as to Bert’s employment one hundred years ago. I’m speculating that the boarding house Bert and his fellow workers lived in was part of, or adjacent to, what we would refer to today as a fast-food take-out and/or home delivery service. The business probably supplied food and water to residents of a small community as well as to workers in the fields of nearby farms.
On the back of the post card, Bert has identified (with a play on words) that he is is driving a water wagon (see accompanying text image).
Bert spent a number of his young adult years working in the Colorado coal mines.