John H. Hemrich was born in Uiffingen, Karlsruhe, Baden, Germany. He was orphaned at an early age but was able to train as a brewer. When he emigrated to America in 1848, he settled as a farmer in Monroe County, New York. Soon he found a position at the newly formed Bartholomay & Co. brewery in the town of Rochester. He worked at the firm for two years, after which he left in the early 1850s for the American frontier.

He established a small brewery in Mount Vernon, Indiana, but a typhoid fever outbreak forced him to leave town. His new brewery was 350 miles to the northwest, in Keokuk, Iowa. In 1851 Keokuk was a growing Mississippi river town situated halfway between Davenport and St. Louis. It was well-positioned for a brewery.  It had good water, fertile farmland, and an endless supply of new customers arriving by riverboat. Sadly for Hemrich, a growing number of these travelers in the 1850s were Mormons who were fleeing nearby Nauvoo, Illinois, on their way to Deseret.

In 1855 Iowa voted itself dry. It was a largely symbolic vote, and the law was unenforced, but this seemed to be the last straw for Hemrich. He relocated once again that summer to Alma, Wisconsin, and built a log brewery right on Main Street. Alma was a brand new town, and Hemrich had just erected her first business. His brewery, called the Union, thrived and lasted long enough to be an incubator for the next generation of Hemrich braumeisters. Andrew, the oldest boy, went on to found (with his father's money) the Bay View Brewery in Seattle, Washington. William took over his father's Union Brewery in 1884. Youngest son Louis became president of the Seattle Brewing and Malting Co. in 1910.

John H. Hemrich died on the 24th of August, 1896, at 73 years of age.