If you have a septic tank and field system, we along with many state and health departments recommend every two to four years depending on the number of people in the household. If your system is an aerobic unit, it is recommended that you have it cleaned every other year. The bacteria in an aerobic system will produce much more waste than anaerobic bacteria.

The first part of a system is a septic tank. It receives the raw sewage from the home. Inside the septic tank, the solids are separated from the liquids. Solids are heavier than the water sink to the bottom of the tank and become part of the sludge layer. Solids lighter than water float to the surface of the liquid in the tank and become part of the scum layer. The tank clear space or clear zone is located between the sludge and scum layers.

As the sludge layer and the scum layer both become thicker, the clear zone becomes thinner. When an excess amount of scum and/or sludge collects in the septic tank some of the solids begin to wash out of the tank with the effluent. These excess solids end up in the second part of an onsite sewage treatment system, or commonly called a leach field.

The excess sewage solids will begin to clog the soil pores of the soil absorption unit so that not as much effluent can be absorbed and treated by the soil. The capacity of the on site sewage treatment system becomes less and less as more solids flow from the septic tank into the soil absorption system and plug the soil pores.

Finally, enough soil becomes clogged so that the soil absorption unit is not able to treat all the sewage that flows into it each day. Resulting in either a sewage backup in the home or sewage surfacing on the lawn depending on the relative elevation of the house and lawn where the soil absorption system is located.

Wet spots in the yard over the septic field, smell/odor, sluggish drains or gurgling in plumbing, and toilets or showers backing up.

Most counties will either do a percolation test or a soil evaluation test to determine the soil category or perk rate. Residential systems are sized by the number of bedrooms and soil type. Commercial units are sized by the amount of employees and soil type.