When should pumping of a septic tank be conducted?

Pumping a septic tank is necessary when the accumulation of solids and scum reaches a level that could compromise the effectiveness of the system. Specifically, if these components exceed 33% of the tank's capacity, the system can become clogged, leading to potential backups and inefficiencies. Regular maintenance, including pumping at appropriate intervals, is essential for preventing failure and extending the life of the septic system. This maintenance guideline is based on the observation that once solids and scum build up to that level, they can impact the function of the tank and the overall system.

The other options do not reflect best practices for septic system maintenance. Relying solely on the presence of bad odors may indicate an issue but doesn't provide a clear guideline for maintenance based on tank condition. Waiting for five years after installation without assessing the tank's level of solids can lead to neglect and possible system failure. Furthermore, pumping only when recommended by a municipal inspector does not establish a proactive maintenance schedule and could result in unnecessary system strain before inspection occurs.