The septic system is an on-site sewage treatment and disposal system buried in the ground. The septic system is comprised of a septic tank and a soil absorption area. When waste material enter a tank several things occur:

Organic solid material floats to the surface and forms a layer of what is commonly called "scum". Bacteria in the septic tank biologically convert this material to liquid.

Inorganic or inert solid materials and the by-products of bacterial digestion sink to the bottom of the tank and form a layer commonly called sludge.

Only fairly clear water should exist between the scum and sludge layers. It is the clear water-and only this clear water-that should overflow into the soil absorption area for the enzymes to take over.