At what percentage full must a holding tank alarm trigger?

The appropriate percentage at which a holding tank alarm should trigger is 85%. This threshold is established to provide enough time for the system operator to respond and take necessary actions before the tank overflows. By setting the alarm at this level, it allows for a proactive approach to waste management.

A trigger point below this percentage, such as 75%, may not provide sufficient warning time, increasing the risk of an overfill situation. Conversely, a trigger point set too high, like 90% or 95%, could lead to situations where the tank is nearly full before anyone is alerted, potentially causing environmental hazards or system failures. Therefore, 85% is the optimal balance to ensure safety and proper function of the septic system.