Which term describes the periodic or continuous surveillance of an on-site sewage system?

The term that best describes the periodic or continuous surveillance of an on-site sewage system is "monitoring." Monitoring involves the systematic observation and checking of the system to ensure that it is operating correctly and efficiently. This process may include measuring performance indicators, checking for leaks or blockages, and assessing the biological and chemical properties of the effluent. Regular monitoring is essential for identifying potential problems before they become severe, ensuring compliance with environmental regulations, and maintaining the health of the system.

While inspection also involves evaluating the state of the system, it typically refers to a more one-time or infrequent assessment. Maintenance refers to the actions taken to keep the system functioning optimally, such as pumping and repairs, and regulation refers to the rules and standards governing sewage systems rather than the act of observing the system's performance. Therefore, monitoring is the most appropriate term for continuous or periodic surveillance of an on-site sewage system.