What is the correct order of the layers in a typical septic tank from bottom to top?

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Multiple Choice

What is the correct order of the layers in a typical septic tank from bottom to top?

A septic tank works by gravity to separate wastewater into three distinct layers. Heaviest solids settle to the bottom, forming sludge. Lighter fats and oils float to the surface, forming scum. The liquid in the middle becomes clarified and flows out as effluent to the drain field. So from bottom to top, you have sludge at the bottom, clearwater (effluent) in the middle, and scum on top. The outlet is designed to draw from below the scum layer to prevent scum from leaving. Regular pumping removes the accumulated sludge and scum to maintain proper function.

A septic tank works by gravity to separate wastewater into three distinct layers. Heaviest solids settle to the bottom, forming sludge. Lighter fats and oils float to the surface, forming scum. The liquid in the middle becomes clarified and flows out as effluent to the drain field. So from bottom to top, you have sludge at the bottom, clearwater (effluent) in the middle, and scum on top. The outlet is designed to draw from below the scum layer to prevent scum from leaving. Regular pumping removes the accumulated sludge and scum to maintain proper function.

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