Q. Is one obligated to search for chametz when in jail, if one won’t be able to burn it, only flush it down?

A. Shulchan Oruch (O.H. 445,1) rules that although the accustomed practice is to burn the found chometz, it can be disposed off in any way. (see Mishna Berura ibid. 5). Someone imprisoned or hospitalized can flush the chometz down.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a