Caplan lived in Seattle with his wife and three children. He maintained a summer residence on Vashon Island in Washington's Puget Sound. In January 1966, following heavy rains in the Pacific Northwest, a mudslide pushed his Vashon home 25 yards from its foundation, dumping much of the house into Puget Sound. An image of Caplan's remaining wreckage was distributed to newspapers as an AP Wirephoto under the headlines, "Mudslide Carries Half a House into Puget Sound" and "It's Now a Split Level".