A 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 by a qualified septic contractor.

The layer of clarified liquid flows from the septic tank to the drainfield. A standard drainfield is made of a series of parallel, underground, perforated pipes and allows wastewater to percolate into the surrounding soil. The gravel and soil act as biological filters as the effluent travels down through the soil layers.

Drainfields or leaching systems are varied and the specific type utilized on a particular property is usually dependent on the soil conditions which exist on the site. The soil must be carefully considered and protected during and after construction and must be evaluated to determine the soil depth to a seasonal high water table. Soil layers that restrict absorption and treatment of sewage are not beneficial.

A treatment plant treats liquid wastes to a higher quality, so it is cleaner and safer before it enters the dispersal area than the discharge from a regular septic tank. The net result for the homeowner is a smaller dispersal area.

What are some of the common symptoms of septic problems?

• Plumbing fixtures may exhibit difficulty in releasing their contents (sluggish drains, bubbling, backups, etc.);
• Large volume discharges such as washing machines, dishwashers or bathtubs cause either a backup or an overflow of sewage above the septic tank or leaching field;
• Foul septic odours;
• A soft or boggy spot in the yard with lush grass growth.

Reasons for a malfunction:

• Excess water use that overloads the system;
• Changes in landscaping that paves over, crushes, or damages a portion of the system.
• Driving over the drainfield with cars or heavy equipment and roots from trees or shrubs candamage the system;
• Changes in position of downspouts, rain gutters and paved areas that drain excess waterinto the area of the yard with the septic system;
• Failure to pump the septic tank to remove excess sludge and scum.

Important information to be obtained:

• Ask for drawings regarding the actual location of the existing septic system;
• Ask for a copy of the septic system permit;
• Ask for the records regarding maintenance of the system. How frequently has the septictank been pumped? What pumping contractor was used? If the system contains a pump, how often has it been maintained? When was the last time the leaching bed was inspected?

Septic tanks should be inspected every year and they usually need servicing every two to three years, depending on the number of people using the system and the volume of daily sewage flow.