When Wilhelm was seven years old, the family moved to the neighboring town of Friedland, where his father built a factory and started the commercial organ business.

However, when his older brother Johann died in December 1842,[4] it was decided that Wilhelm would be the one to inherit his father's business and continue the work he had started building organs.

[5] In 1855, Sauer took over the management of the German crown branch in his father's factory, which had been opened there for the Prussian market in order to avoid customs duties.

[7] In 1883, Sauer was awarded the Distinction of Akademischer Künstler and the following year, on 18 April 1884, he was named by the cabinet as "Royal Organ Builder".

His grandson, Wolfgang Sauer (1920–1989), went to the United States in 1964 and became a professor of German history at the University of California, Berkeley.