When William Hemann was born on 25 June 1899, in Stacyville Township, Mitchell, Iowa, United States, his father, Peter Theodor Hemann, was 35 and his mother, Elisabeth Steiger, was 31. He married Christina Koenigs on 27 January 1924, in Mitchell, Iowa, United States. They were the parents of at least 2 sons. He lived in Stacyville, Mitchell, Iowa, United States in 1910 and Mitchell, Mitchell, Iowa, United States in 1925. He died in November 1970, in Mitchell, Iowa, United States, at the age of 71, and was buried in Meyer, Mitchell, Iowa, United States.