Ontario Operator-in-Training (OIT) Practice Exam

What is a septic tank effluent gravity system?

1. A system where sewage flows using pumps only

2. A gravity-driven system using pumps for transport

3. A non-pressurized system for effluent disposal

4. A system that relies on filtration and chlorination

The correct answer is: A non-pressurized system for effluent disposal

A septic tank effluent gravity system is characterized by its operation as a non-pressurized method for disposing of effluent. In this type of system, sewage is first collected in a septic tank where solids settle at the bottom and undergo anaerobic digestion. The liquid effluent, which is treated to some extent during this process, then flows out of the tank by gravity to a leaching field or drain field for further treatment and absorption into the soil. The emphasis on being non-pressurized highlights that the movement of the effluent relies solely on gravitational forces, rather than mechanical means such as pumps or pressurized lines. This distinction is crucial because it indicates a simpler and often more reliable method of effluent disposal that is less susceptible to mechanical failure. The incorrect answers point to other systems that incorporate either pumps for moving sewage or additional treatment processes like filtration and chlorination, which are not part of a standard septic tank effluent gravity system. Thus, option C accurately captures the essence of how this particular system functions.