Septic Fields

Excerpt from the National Small Flows Clearinghouse

Did you know about 25 percent of the U.S. population relies on decentralized--or onsite-- wastewater treatment systems? About 95 percent of the onsite wastewater disposal systems are septic tank systems.

If you own a septic system, it is important that it be properly maintained. How often you need to pump the solids out of your septic tank depends on three major factors:

1.  The number of people in your household;                                              

Time Table

Tank Size

Number of People Using the System
1                  2                  4                 6                  8

            ------------------ Number of Years ------------------


5 2 1 <1
1,000 12 6 3 2 1
1,250 16 8 3 2 1
1,500 19 9 4 3 2

2.  The amount of wastewater generated (based on the number of  people in the household and the amount of water used); and
3.  The volume of solids in the wastewater (e.g., using a garbage disposal will increase the amount of solids).

Although your septic tank absorption field generally does not require maintenance, you should adhere to the following rules to protect and prolong its functional life:
Do not drive over the absorption field with cars, trucks, or heavy equipment.
Do not plant trees or shrubbery in the absorption field area, because the roots can get into the lines and plug them.
Do not cover the absorption field with hard surfaces, such as concrete or asphalt. Grass is the best cover, because it will help prevent erosion and help remove excess water.
Do divert surface runoff water from roofs, patios, driveways, and other areas away from the absorption field.

The following drawings will hopefully give you enough information that will enable you to understand the workings of a septic field a little bit better.

Click on the image to see a larger picture

 tank1.gif (7919 bytes)  Here is a cross section view of a septic tank (pig).

vabsf.gif (8008 bytes)  This drawing will give you an idea of a standard septic field layout.

trench.gif (19549 bytes)  This is a cross section view of a distribution line in the septic field