Knapp, the son of Baptist missionaries Douglas and Evelyn Knapp, spent much of his childhood in East Africa. He studied piano with local teachers and was educated at the Rift Valley Academy before completing high school in Deland, Flordia. He went on to study at the North Carolina School of Fine Arts and privately with a Juilliard instructor. After two years he returned to Tanzania to be with his parents and took the opportunity to perform, including a concert at the United States embassy in Addis Ababa, Ethiopia.
Knapp returned to the United States and completed a master's degree in piano at Samford University. He spent his career in music performing for churches, tuning pianos, and teaching private students. One of those students, Patricia Powell, became a life-long friend and travel companion. Knapp also composed music for the piano and was chosen as a featured performer for the Yamaha "Disklavier" digitally-controlled player piano.
- "Walter Knapp" obituary (December 1, 2017) The Birmingham News