What is a Septic System and How Does it Work?

The way in which a septic system works is pretty straight forward. They use natural processes and time to effectively break down household waste. This protects not only homeowners and their families, but also their property and the environment.

Keeping your septic tank in proper working order begins with good septic tank maintenance.

Basically, a septic system is smaller version of a municipal sewage treatment plant.

These types of systems are common in rural settings and areas that do not have easy access to city municipal services.

The key to this type of sewage system is the septic tank, without it, the outhouse would still be a common site along the many back roads and country lanes.

A septic system is made up of two main components; the drain field and the septic tank. It works by running the waste effluent through various stages inside the chambers that separate its internal makeup. The first chamber is the largest as it collects all the household waste water from the inlet pipe. As organic solids, commonly called sludge, enter the first chamber, they settle to the bottom. The sludge is then broken down and digested by different bacteria, some anaerobic but mostly facultative bacteria that produces a combination of carbon dioxide and methane gas. This helps stabilize the sludge and stops it from rotting. Most of the sludge will stay on the bottom of the tank, but a small amount will float forming a layer of scum.

All septic tanks are designed to allow the sludge to spend a maximum amount of time being exposed to the digestive bacteria’s. They do this by locating the inlet, overflow and outlet pipes diagonally across from each other. The pipes for the overflow and outlet are also vertically placed, forcing waste material to flow upward between stages. This makes the effluent travel a longer distance before entering the next phase of processing, furthering the break down of waste products during each phase.

After the semi-processed waste water leaves the first chamber via the vertical pipe overflows it enters the second chamber, forcing the waste water to go upward preventing large solids from getting into the second chamber. The same process is in place in the second chamber as in the first, as the organic matter is further digested and settled by bacterial microorganisms. The second chamber is normally about half the size of the first chamber and as a result, the effluent only spends about half as long processing before being discharged into the drain field.

The outlet to the drain field is located in the opposite corner from the overflow into the second chamber. Only waste water should be flowing into the drain field as all solids should have settled out into one of the two septic chambers. The waste water is further filtered and purified by the soil in the drain field before it is taken in by plant roots or filters downward to any ground water that exists in the area. The size of the drain field will be dependent on soil types and porosity.

Most septic tanks and systems are designed to use the pull of gravity to allow a natural flow of waste effluent from the home to its final destination in the drain field. In some instances, the lay of the land may not be conducive to a gravity fed system so a pump or pumps may be needed.

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