How Homesteading Septic System Works is detailed in this outline of the step by step prcess that deals with human body waste.

It is an honest question. How does a septic tank function? We know what it is, but not what it looks like inside. The tank is made out of concrete or steel (or even hard plastic) that is sturdy enough to hold gallons of waste. The water and waste is separated under it is sucked out of the tank often so the tank does not collect up too much of the extra sludge that can clog the whole thing up. The tanks also have several levels inside so it can absorb everything carefully since the waste comes in from the top. With the additional things inserted to break things up into the smallest particles, it makes things much easier to control and suck out when necessary.
Underneath the tank, which serves as a second half to the whole system, channels filled with grit and pipes are buried and filled with cleaned water. Pumps equally release the water to these pipes. This is where the bacteria can be caught while water can seep into ground and drained into the reservoirs. In terms of the soil, it can be shallow, water-resistant (as in lack of drainage), or very leaky to suck in every drop of water. Another option is to have a mound rather than flat land and pipes circle around under the mound, which could make it easier in some cases with drainage.
