Septic tank pumping will be discussed in a later section. The disposal field generally consists of a network of perforated pipes laid in gravel-filled trenches, as shown in Figure 3. After partial treatment in the septic tank, the sewage effluent flows into the distribution box or a series of drop boxes, then out through the perforated pipe and into the gravel-filled trenches. The gravel acts as A media for aerobic bacteria and other organisms to feed on the sewage. In the soil below the disposal trenches, soil particles, including disease causing bacteria are filtered out.
Soil bacteria destroy some of the pollutants.
Other pollutants become bonded to clay particles. In order to take proper care of a system the homeowner must know where it is located. If the septic tank's access manhole is at ground level, it should be easy to locate. To locate the septic tank, look under the house or in the basement to find where and in what direction the sewer pipe goes out. Any likely spot can be probed with a metal rod.