Septic Systems: What you need to know
What are the parts of a septic system?
Most septic systems are the conventional type, consisting of a septic tank and a
drainfield. The tank, which usually has a capacity of about 1,000 gallons, is buried in the ground
along with a number of gravel-filled trenches. Either the front yard or the backyard of a home
must be large enough to accommodate the tank and drainfield. Generally, at least 1 acre of land is
needed for a properly functioning septic system. The cost of installing a conventional septic
system ranges from $4,000 to $7,000.
How does each part of the septic system function? How can I tell if my septic system is not
functioning safely or properly?
Household wastewater from the kitchen, bathrooms, and laundry area flow into the septic tank.
Solids remain in the tank, and the liquidcalled septic tank effluentflows out of the tank to the
drainfield where it leaches through the soil. In a properly functioning septic system, the germs
(bacteria and viruses) in the septic tank effluent are removed in the soil treatment zone by
filtering and by soil microorganisms before reaching the groundwater. Some chemicals such as
nitrates, however, are not typically removed in the soil treatment zone. Not all soils, however,
are capable of absorbing and purifying septic tank effluent. An odor of sewage and a wet area
around the drainfield are signs that the septic system is not functioning properly. Also,
contaminated well water may be a sign that your septic system is not doing its job.
What maintenance does a septic system need?
The biggest maintenance task is pumping the solids from the tank. After a few years, the solids
that accumulate in the tank need to be removed and disposed of properly If not removed, the solids
will spill over into the drainfield and clog the soil. With proper maintenance, a septic system
can work efficiently for many years. These factors determine how often your tank will need to be
pumped:
- the size of your tank
- the volume of your wastewater
- the amount of solids in your wastewater
Here are some tips for proper maintenance:
- Limit the use of garbage disposals
- Do not use too much water. (A good limit is 50 gallons per person per day.)
- Do not add materials such as facial tissues, hygiene products, or cigarette butts to wastewater.
- Do not pour cooking oils or grease down the drain.
- Maintain a grass or other vegetative covering over the drainfield.
- Keep autos and heavy equipment off of the system
What should not be flushed through a septic system?
The following substances should not be put in the septic system:
- cooking grease, oils, or fats
- pesticides
- paints
- paint thinners
- solvents
- disinfectants
- other household chemicals
Cooking grease, oils or fats should be placed in a container and put in household garbage that will be landfilled. Pesticides, paints, paint thinners, solvents, disinfectants and other household chemicals are toxic substances that threaten ground water quality. They may also kill the microorganisms that help purify the sewage. For information on safe disposal of these chemicals, contact your county office of the N.C. Cooperative Extension Service.