Where should the outlet baffle screen or filter draw liquid from?

The outlet baffle screen or filter should draw liquid from the "clear zone" of the septic tank because this area is designed to contain the highest quality effluent, which is the liquid that has undergone initial treatment in the tank. The clear zone is located just above the sludge layer and below the water surface, where the liquid has settled to remove most of the solid particles and contaminants.

By taking water from the clear zone, the system ensures that the effluent sent into the next treatment phase—such as a drain field or leach field—is as clean as possible. This helps to protect the receiving environment and maintain the effectiveness of the subsequent treatment processes.

Drawing from the sludge layer would introduce not only solids but also potential pathogens into the system, while drawing from an effluent pump chamber would not be relevant for a septic tank's outlet baffle, as that area is responsible for pumping treated wastewater rather than filtering it within the tank. Finally, sourcing liquid from the soil surrounding the septic system is not appropriate, as it would eliminate the necessary treatment the effluent already undergoes in the tank.