Abstract: A filter life indicator is described herein utilizing a constant flow channel and a flow actuated switch incorporating a reciprocating magnetic member to start a timer. Circuitry monitors this timer and actuates a visual or audible indicator when the filter needs to be replaced. The timer consists of a pulse generator, a scaling circuit, a counter, and a comparator. During flow pulses are counted and compared to a preset limit. And to accommodate filters having differing life expectancy, modules corresponding to each filter are installed to change the scaling circuit.