What is a Septic system?

A septic system is used in areas with no connection to main sewage pipes provided by local governments or private corporations. The system is built specifically for one house. Septic systems use soil to treat small wastewater flows.

What are the components to a septic system?

A typical system contains a septic tank, a distribution box and a rock-and-gravel-lined absorption field (drainfield). All are connected by pipes called conveyance lines.

Septic tanks are made of concrete, fiberglass or plastic. They are usually buried, and watertight and are designed to hold a minimum of 750-1000 gallons of sewage. Their purpose is to temporarily hold the wastewater as solids and liquids separate. The solids, known as sludge, collect at the bottom of the tank, while scum floats to the top of the liquid. The sludge and the scum will remain in the tank and need to be pumped out every 2-4 years on average.

The wastewater, or effluent, will pass through the tank to the distribution box. The distribution box separates the flow of the water into the network of underground, perforated pipes in the absorption field. The effluent passes through the holes in the pipes in to the rock-and-gravel zone. It will be stored there until it is absorbed by the soil.

The absorption field treats the wastewater through physical, chemical and biological processes. The soil acts as a natural buffer to filter out bacteria, viruses and excessive nutrients. The wastewater is treated before reaching the ground water.

How do septic systems work?

Households that are not served by public sewers usually depend on septic systems to treat and dispose of wastewater. Septic systems represent a significant financial investment and if cared for properly it will provide years of reliable, low-cost service.

A failing system can become a source of pollution and public health concern, causing property damage, surrounding ground and surface water pollution, and disease outbreaks. Once your septic system fails to operate effectively, you may need to replace it, costing you thousands of dollars. Plus, if you sell your home, your septic system must be in good working order. Therefore, it makes good sense to understand and care for your septic system.

There are many different types of septic systems that fit a wide range of soil and site conditions. The following will help you understand the main components to keep it operating safely:

A standard septic tank system has three main parts:

The Septic Tank

A septic tank’s purpose is to separate solids from the wastewater, store and partially decompose as much solid material as possible, while allowing the liquid (or effluent) to go to the drainfield.

The Drainfield

After solids settle in the septic tank, the liquid wastewater (or effluent) is discharged to the drainfield, also known as an absorption or leach field.

The Soil

The soil below the drainfield provides the final treatment and disposal of the septic tank effluent. After the wastewater has passed into the soil, organisms in the soil treat the effluent before it percolates downward and outward, eventually entering ground or surface water. The type of soil also impacts the effectiveness of the drainfield; for instance, clay soils may be too tight to allow much wastewater to pass through and gravelly soil may be too coarse to provide much treatment.