David Werkendam was a son of Mozes Izaak Werkendam and Duifje Turfkruijer. He married Hilletje Bremer in 1915 in Amsterdam. They divorced in 1938. They had five children, among whom Max, Samuel, Dora and Philip (who passed away in 1925). He remarried on 21 August 1940 in Amsterdam to a catholic woman. Hildegard Lorenz was his stepchild.
Stadsarchief Amsterdam, archiefkaart David Werkendam