Frequently Asked Questions About Septic Tanks

What are the components of a private septic system?
The things that are the most obvious are the things seen every day - the sinks, toilets and pipes in a normal house. What are not visible are the things that are underground; and the ground itself, greatly impact how a septic system works.

The two main individual components of a regular septic system are the septic tank and leach field. There may also be other materials used with your system; depending on how old the system is, such as distribution boxes, alternating valve & drywells.

Bacterial action takes place in the septic tank where the end products are mainly water, gases, and undigested material. The undigested materials consist of sludge that sinks into the bottom of the tank and scum that floats to the top of the tank. The septic tank contains baffles that prevent any scum that float to the surface and sludge that settles to the bottom from passing out of the tank and into the leach field. The soil also acts as a filter to remove any small amounts of solids that may be carried along with the liquid. The sludge in the bottom of the tank mist be periodically pumped out and properly disposed of.

There are other kinds of systems for special situations, but the septic tank and leach field is the most widely used system in our area.

Care and Maintenance
Conventional septic systems are not entirely carefree. The undigested solids (sludge) in the bottom of the septic tank should be pumped out every two to four years, depending on usage and tank size. If the sludge is not removed periodically, it will eventually carry over into the leach field and cause the field to fail and may also back up into the home.

A well-designed system can handle a reasonable amount of normal household chemicals such as drain cleaners, laundry detergent and bleach, but excessive usage can be detrimental to your septic system. You should avoid putting chemicals that are toxic to the bacteria into the system, such as paint thinner, solvents, insecticides, etc. Cooking fats and grease should also be avoided. If a garbage disposal is used, more frequent tank pumping may be needed.

Why septic Systems Fail
If the liquid effluent cannot soak into the soil surrounding the leach field, sewage may back up into the system and overflow into the house or puddle on the surface of the ground. There are several possible causes for this problem.

1. Poor soil conditions; faulty design or installation
   a leaching system placed in unsuitable soil, a system that is too small for the house it serves, or an improperly constructed system may lead to early failure.
2. Soil Clogging
   If sludge or scum is allowed to escape into the leach field; the soil will quickly become clogged. If this happens, the liquid will no longer soak, or percolate, into the soil. This condition can be caused by broken baffles in the septic tank that allow sludge or scum to escape. Failure to have the tank pumped can also lead to a situation where the sludge and scum overwhelm the baffles.
3. High Water Table
   During wet or abnormally wet seasons groundwater may rise into the leach field and force sewage upward to the ground surface. This condition may mean the system has to be re-installed at a higher level. It may also be possible to intercept the high groundwater with a series of drains around the system called "curtain drains."
4. Roots
   The roots of trees and bushes planted too close to the system can sometimes enter and block the pipes of the system. Removal of the plants and clearing the pipes of the roots is usually required.
5. Physical Damage
   Trucks or heavy equipment passing over the system can damage pipes and joints to the point of rendering the system inoperable. You should be aware of the location of the system and direct traffic to avoid such damage.

How long should a septic system last?
You can expect a conventional septic system, such as that being described here, to last about 30 years. Some systems last much longer and some systems can fail earlier for reasons like those listed above. Other things can also affect the life of a septic system. For example, a system may have been providing satisfactory service for a previous owner for many years, only to fail shortly after you have bought the house. If the previous owners were a working couple with no children, the system was probably not heavily used. If yours is a family of six, the added load could push a marginal system over the edge and into failure.

What are the signs of a failing system?
Sewage backup into the home is one possible sign of a failing system. However, backup can also be simply the result of a blockage somewhere between the house and the septic tank (this is relatively easy to fix). Another possible sign of failure is a smell of sewage outside the house. If this smell is more noticeable after a lot of water has been put into the system - multiple showers or several loads of laundry (if the laundry waste discharges into the septic tank), for example - this may be an indication that the leach field is failing. The smell may also be accompanied by a "spongy" feeling in some areas of the leach field. The "spongy" feel may be caused by water and waste being pushed to or near ground level. If ponding water is also seen, this is called "breakthrough" and is an almost positive indication of failure of one or more parts of the system. This smell, however, can also originate at the plumbing vent. In either case, further investigation is warranted.