The name, which is spelled a variety of ways (Bacharach, Bachrach, Bacherach, Backerack, etc.) is presumed to come from the town of Bacharach, on the Rhine in Germany. For the purposes of this article, I will standardize on the Bacharach spelling, but I mean to include all spelling variations.
Since more than one Jewish family could have originated in Bacharach at the time surnames were adopted in the early 1800s in Germany, it’s possible that multiple unrelated families who were originally from there could have taken the surname in other parts of Germany. This is likely to be the case for lots of toponyms (names taken from geographic locations). For example, every family who became Berliner probably once lived in Berlin, but not every Jewish family from Berlin was necessarily descended from the same male ancestor. For more on how surnames were adopted, see the JewishGen Name FAQ and the JewishGen InfoFile on the subject.
Lars Menk’s book A Dictionary of German-Jewish Surnames, which is invaluable for doing serious research, lists dozens of locations where he found the name, at least half of which are prior to the mass adoption of surnames across western Europe. Because the Bacharach name was in use as early as the 1400s and widely dispersed by the 1600s, there may be reason to believe there are connections among the different families who carry the name. It was exceedingly unusual at that time for Jews to pass a surname down from generation to generation, unless it showed a connection to a famous rabbi or a distinguished lineage of some other sort. There were a few semi-famous rabbis who had the Bacharach surname and possibly originated in the Rhine area around the town of Bacharach. One was Rabbi Abraham Samuel Bacharach (ca 1575-1615) (see his Wikipedia entry) who married the granddaughter of the famous chief rabbi of Prague, Judah Loew ben Bezalel and was the rabbi of Worms. His grandson, Rabbi Yair Chayim Bacharach (1639-1702) (see his Wikipedia entry) was also well-known. It’s possible that the various branches of their families carried on the surname because of the connection to this illustrious family.
From Lars Menk’s book, in the section entitled “Historical Development of the Concentration of Surnames in Some Areas”:
Thus, the surname BACHARACH (Bacherach; Bachrach) that indicates an origin in the town of the same name situated on the Rhine River was originally adopted in the cities of Worms (1449), Mainz (1455) and Frankfurt am Main (1516). Then, carried by a rabbinical dynasty, it spread to numerous locations in central and eastern Europe. Later, in the early 17th century, it appeared in and around Göttingen (then a southern part of the Duchy of Braunschweig). In the middle of the 17th century, this surname could be found in and around Kassel in the county of Hesse-Kassel (today in Northern Hesse).
From A Dictionary of German-Jewish Surnames, Copyright 2005 by Lars Menk, excerpted by permission of Lars Menk