True or False: All tanks must maintain an operating liquid capacity of 60%-70% of the interior volume of their absorption lines.

The statement is true because maintaining a specific operating liquid capacity is crucial for the proper functioning of septic systems. An operating liquid capacity of 60% to 70% ensures that there is enough liquid to effectively saturate the absorption lines, promoting optimal anaerobic bacterial activity that breaks down solids in the waste. This range also helps to prevent issues such as clogging or oversaturation of the absorption area, which can lead to system failure and environmental contamination.

In septic systems, if the liquid level is too low, the system cannot function effectively, as the microorganisms will not thrive without sufficient moisture. Conversely, if the liquid level is too high, it may lead to surface flooding and effluent backing up into the tanks, posing health and environmental hazards. Therefore, adhering to the 60%-70% capacity guideline is an important operational standard that ensures both the efficiency and longevity of the septic system.