It is said that the origin of their surname was Mizunogo, Kasugai County, Owari Province (present day Mizuno, Seto City); however, a theory recorded in the 'Kanseifu' claims that it was Mizuno no sato in Saga, Kyoto.
苗字の地は尾張国春日井郡水野郷（瀬戸市水野）とされるが、京都嵯峨水野の里とする説が「寛政譜」には記されている。