Abstract: A two stage alarm system for detecting rising levels of sludge in septic tanks, and similar sedimentary tanks. The system, to detect a first or “caution” level, and a second or “critical” level of sludge, relies upon a pair of vertically positioned weight sensitive switching mechanisms which, when triggered by the rising levels of sludge, will send appropriate signals to a remote alarm mechanism, such as at the residence, to activate a “yellow” and/or “red” light, for example, thus alerting the owner of the tank to the need for remedial action.