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Septic Systems

What is a septic system? How do I maintain one?

A septic system is a highly efficient, self-contained, underground wastewater treatment system. Because septic systems treat and dispose of household wastewater onsite, they are often more economical than centralized sewer systems in rural areas where lot sizes are larger and houses are spaced widely apart. Septic systems are also simple in design, which make them generally less expensive to install and maintain. And by using natural processes to treat the wastewater onsite, usually in a homeowner's backyard, septic systems don't require the installation of miles of sewer lines, making them less disruptive to the environment.

A septic system consists of two main parts-a septic tank and a drainfield. The septic tank is a watertight box, usually made of concrete or fiberglass, with an inlet and outlet pipe. Wastewater flows from the home to the septic tank through the sewer pipe. The septic tank treats the wastewater naturally by holding it in the tank long enough for solids and liquids to separate. The wastewater forms three layers inside the tank. Solids lighter than water (such as greases and oils) float to the top forming a layer of scum. Solids heavier than water settle at the bottom of the tank forming a layer of sludge. This leaves a middle layer of partially clarified wastewater.

The layers of sludge and scum remain in the septic tank where bacteria found naturally in the wastewater work to break the solids down. The sludge and scum that cannot be broken down are retained in the tank until the tank is pumped. The layer of clarified liquid flows from the septic tank to the drainfield or to a distribution device, which helps to uniformly distribute the wastewater in the drainfield. A standard drainfield (also known as a leachfield, disposal field, or a soil absorption system) is a series of trenches or a bed lined with gravel or course sand and buried one to three feet below the ground surface. Perforated pipes or drain tiles run through the trenches to distribute the wastewater. The drainfield treats the wastewater by allowing it to slowly trickle from the pipes out into the gravel and down through the soil. The gravel and soil act as biological filters.

Septic System and Drainfield

Septic System Maintenance

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:

  • The number of people in your household;
  • The amount of wastewater generated (based on the number of people in the household and the amount of water used); and,
  • 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.

Don't Flush It

Homeowners wanting to take good care of their septic systems should make note of the following items that should never be flushed down the drain or toilet. These items can overtax or destroy the biological digestion taking place within the system or clog pumps and pipes.

Take care not to flush the following:

  • hair combings, coffee grounds, dental floss, disposable diapers, or kitty litter,
  • sanitary napkins, tampons, cigarette butts, or condoms,
  • gauze bandages, fat, grease, or oil, paper towels,

and NEVER flush chemicals that could contaminate surface and groundwater, such as:

  • paints, varnishes, thinners, waste oils, photographic solutions, or pesticides.

Basic Septic System Information

Basic Wastewater Characteristics – Basic questions about wastewater characteristics and their potential impact on public health and the environment are addressed.

So... now you own a septic system - How a septic system works, to flush or not to flush…

The care and feeding of your septic system - When to pump the septic tank, how to reduce water use, and health tips.

Groundwater protection and your septic system - How septic systems recharge groundwater, separation distances, and contaminant information.

Maintaining Your Septic System: A Guide for Homeowners – Proper operation and maintenance of your septic system can have a significant impact on how well it works and how long it lasts, and in most communities, septic system maintenance is the responsibility of the homeowner.

Septic Systems: A Practical Alternative for Small Communities – When properly designed, installed, and maintained, septic systems can be the most cost-effective and efficient method of wastewater treatment a homeowner can choose.

Septic Tank Enhancements – Options available to enhance the efficiency of your septic tank and/or to improve convenience of maintenance are discussed.

Landscaping Septic Systems – This fact sheet was published by the University of Minnesota, College of Agricultural, Food and Environmental Sciences that ran in response to an NSFC technical call.

Soil Characteristics – Demystifying Dirt – Soil types and classifications are explained and how their differences impact onsite wastewater treatment are discussed.

Soil Evaluation Techniques Q&A – How is the soil on my site determined to be suitable for an onsite wastewater treatment and disposal system?

Roof Drains and Septic Systems – The local sanitarian said I couldn't tie my roof drains into my septic system? Why not? It's just getting rid of rain water, so what would it hurt?

First Aid for a Flooded Septic System – Recommendations for homeowners on how to keep their septic system functioning before, during, and after flooding are provided.

Septic Tank Additives – Different types of additives are discussed as well as research.

Alternative Household Cleaning Solutions – This fact sheet identifies alternative cleaning solutions for everyday home maintenance comprised of natural ingredients.

Septic Systems and Source Water Protection – How a septic system works and how the homeowner can help improve area water quality is discussed.

Quality Control for Homeowners – This issue helps homeowners give thought to quality control during installation of their treatment system.

Septic Tank Inspection Q&A - Inspections are a necessary part of the operation and maintenance of a septic tank. This article provides a guide on how to get one.

Buying or Selling a Home with an Onsite Wastewater System – If you are selling or buying a house that uses a septic system for its wastewater treatment, there are things both parties need to know to make the transaction go smoothly.

Local Man with Failing Septic Gets Help – When Dr. Todd Crocco saw wet, smelly sewage surfacing in his front yard, he knew he had a problem.