Drinking water level alarm lamp

A drinking-water level alarm lamp for being placed in a water feeder includes a watertight casing including therein a lamp, a rolling ball tilt switch, a battery and a weight. When the water feeder contains drinking water, the drinking-water level alarm lamp half floats above the water by virtue of the inner space of the watertight casing and the weight. When the water feeder contains no drinking water, the drinking-water level alarm lamp lies at a bottom of the water feeder. The drinking-water level alarm lamp uses the presence and absence of the drinking water in and from the water feeder to change a position of the drinking-water level alarm lamp, so that the rolling ball tilt switch in the drinking-water level alarm lamp is accordingly switched to turn on or off the lamp.