Which of the following is a common maintenance task for septic systems?

Pumping out the septic tank is a crucial maintenance task for septic systems because it helps to manage the buildup of solids that accumulate in the tank over time. Septic tanks are designed with a specific capacity, and when they are not regularly pumped, the solids can overflow into the drain field, causing potential system failures and environmental hazards. By maintaining a routine pumping schedule, typically every 3 to 5 years depending on usage and tank size, homeowners can ensure their septic system operates efficiently, prolong its life, and prevent costly repairs.

In contrast, the other options do not reflect standard maintenance practices for septic systems. Regularly fertilizing the drain field is unnecessary and can lead to disturbances in the soil and microbial environment critical for the system's function. Adding more soil to the drain field is not a common practice and does not address the core function of the septic system effectively. Inserting chemicals to enhance breakdown can interfere with the natural bacterial processes within the septic tank that are responsible for breakdown of waste. Therefore, proper septic system maintenance focuses on pumping out the tank and maintaining the natural biological processes rather than adding substances or making unnecessary alterations to the system.