Which of the following is NOT a characteristic required for all septic tanks?

The requirement for septic tanks does not include having to incorporate bacterial treatment as a specific characteristic. While bacteria play an essential role in the natural breakdown of organic matter within the tank, the design and functionality require that the tank is not designed to actively manage or provide additional bacterial treatment. The other features listed—having an effluent baffle screen, monitoring and service access, and being watertight—are crucial for ensuring that the system operates effectively and prevents leaks, as well as allowing for necessary maintenance and inspections. These features protect public health and the environment by ensuring that wastewater is adequately contained and treated before being released into the environment.