Abstract: The alarm mechanism of the invention signals the absence of a liquid from a source of aqueous liquid. The alarm mechanism comprises an alarm body having an inlet port and an outlet port; the inlet port in liquid communication with a source of liquid, the outlet port in liquid communication with a use locus. The alarm mechanism additionally comprises a float chamber placed in liquid parallel communication with the inlet port and the outlet port. The float chamber containing a float operably connected to an alarm. The float, when a chamber is filled with fluid, disables the switch from generating a signal. The float, as the chamber is emptied of liquid, reaches a position and is detected energizing the switch to send a "low or empty product" signal. The apparatus operates by passing liquid through the body.