A flush assembly for a toilet with a tank can include a rigid siphon body with a siphon inlet, a siphon outlet, and a siphon passage. An outlet assembly can be coupled to the siphon outlet to provide a liquid flow path between the siphon outlet and a flush port of the tank. The rigid siphon body can be configured to float within the tank and to be submerged to establish a siphon-driven flow of liquid from the tank to the flush port to flush the toilet.