While at Johns Hopkins, he met future director/screenwriter Matthew Robbins, cinematographer Caleb Deschanel, and philosopher Andrew Feenberg, with whom he staged a number of happenings. In 1965, Murch and Robbins enrolled in the graduate program of the University of Southern California's film school, encouraging Deschanel to follow them. There all three encountered, and became friends with, fellow students such as George Lucas, Hal Barwood, Robert Dalva, Willard Huyck, Don Glut and John Milius; all of these men would go on to be successful filmmakers. Not long after film school, in 1969, Murch, Lucas, and others joined Francis Ford Coppola at American Zoetrope in San Francisco. Murch and his family settled in Bolinas, California, in 1972.
Murch married Muriel Ann "Aggie" Slater at Riverside Church, New York City, on August 6, 1965. Directly after getting married, the couple took a motorcycle trip across the United States. They have now lived in Bolinas, California, since 1972 and have 4 children: Walter Slater Murch, Beatrice Louise Murch, Carrie Angland, and Connie Angland.