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What is Septic Tank Effluent?

R. Anacan
R. Anacan

Septic tank effluent is the wastewater that is discharged or flows out of a septic system. Wastewater is any liquid or water that is produced from a building and may contain waste from sinks, bathtubs, toilets and appliances such as washers and dishwashers that use water. Wastewater may contain contaminants that are harmful to humans, animals and plants; therefore it is important that wastewater is treated adequately before it is released into the environment. A septic system is a simple, yet effective means of treating wastewater.

A septic system consists of two main components, the septic tank and a drain field. A septic tank is a large, waterproof container that is generally located below ground level, although some locations may require an above ground system. The septic tank acts as the holding area for the wastewater produced by a home or business. As water enters the tank, bacteria in the tank start to break down solids present in the wastewater.

A septic system consists of a septic tank and a drain field.
A septic system consists of a septic tank and a drain field.

As solids in the wastewater are broken down, the wastewater in a septic tank divides into three main parts. The first consists of solids, known as sludge, that sink to the bottom of the tank. The second component consists of particles and foam that float to the surface of the water, which are typically known as scum. In between the scum layer on the surface and the sludge on the bottom is a layer of partially treated water.

When a septic system is working properly, the water is released into the drain field while the solid matter remains in the tank. The drain field is the area where septic tank effluent is released. As new water enters the tank, it displaces the water already in the tank and forces it out in the drain field. A drain field typically consists of a series of buried perforated pipes that septic tank effluent flows through. The small holes in the pipe allow the septic tank effluent to slowly drain back into the ground, where the treatment process continues as effluent filters through the soil and back into the groundwater supply.

Over time the solids in the tank will build up, therefore it is critically important for the overall operation of the septic system and the well-being of anyone close to the septic system, that the contents of the tank are pumped out and removed on a consistent basis. An improperly maintained septic tank system can lead to waste flowing back into a building or in wastewater flowing into the drain field at a rate higher than the field can effectively absorb. When this occurs the area above the drain field may be flooded with improperly treated septic tank effluent.

Discussion Comments


@Markerrag -- A sewer is always preferable, but there are times when hooking into one simply isn't possible. You might buy a house in a new subdivision out in the county rather than in town, build a home in a rural area, etc.

Fortunately, septic tank technology has improved and maintenance isn't as big of an issue as it once was.

Oh, and if you do have a septic tank, make sure to use one of those products that you flush down your toilet regularly to break down waste in your septic tank. Some of that stuff can save you a lot of trouble.


This article helps illustrate why septic tanks are usually more trouble than they are worth. When they get too full (and that happens far more often than you might think), you get a swampy, stinky mess on the ground near the tank that can make your yard very unpleasant.

The troublesome septic tank is one of the many reasons people in unincorporated areas tend to join cities and why neighborhoods will get together and try to convince a city to run sewer services to their homes.

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    • A septic system consists of a septic tank and a drain field.
      By: gozzoli
      A septic system consists of a septic tank and a drain field.