The tank is an essential part of the septic system. The two-chamber design shown here is popular because it’s uncomplicated and reasonably effective. However, flooding or overloading the tank can still send undigested material into the drain lines, clogging the absorption field. The latest tank designs have deep holding chambers and internal convolutions to encourage solids to settle out from the flow.
ILLUSTRATION: DON OSBY
The absorption-field trenches should be carefully planned and laid out to suit the site. Each line is buried in a bed of gravel.
Illustration shows possible layouts for an absorption or drain field.