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What Is Septic Tank Aeration?

Gae-Lynn Woods
Table of Contents

Septic tanks are used in locations that lack access to a city-provided sewage system. Several types of septic systems are available, and one alternative to traditional septic tanks is the aerobic septic tank.

Water processed through septic tank aeration is used to irrigate lawns.

The aerobic system uses an aeration process to digest household waste faster than the rate at which this occurs in traditional septic tanks.


Septic tanks use microorganisms to process liquid and solid household waste, reducing the level of harmful pathogens before the processed waste, or effluent, is released into the environment. Two types of microorganisms, aerobic and anaerobic, can perform this function. Anaerobic microorganisms operate in an oxygen-free environment such as that found in traditional septic systems, while aerobic microorganisms require oxygen provided through aeration to work effectively. According to the Environmental Protection Agency (EPA), aerobic septic tank systems use the superior digesting power of aerobic microorganisms to treat waste more efficiently than traditional systems do, allowing for dispersal of the treated effluent to the ground’s surface.

How It Works

Aerobic septic tanks use an air compressor or blower system to force air into the main treatment tank, where it mixes with the tank’s solids and wastewater. This is septic tank aeration, and oxygen in the air sustains the aerobic microorganisms digesting the waste. The National Park Service notes that the use of this system results in processing speeds up to 20 times faster than traditional systems. Unprocessed solids either settle to the bottom of the septic tank as sludge or flow through a settling chamber, from which they eventually return to the main septic tank. Some systems use a pretreatment chamber to separate solids such as toilet paper and grease that can clog the unit.

When to Use Aeration

The National Small Flows Clearinghouse recommends installing an aerobic septic system if your property does not provide adequate space for a drainfield or if your soil is unsuitable for septic drainage. Through the aeration process, aerobic systems provide a higher quality effluent, and you might consider an aerobic septic system if you live near a body of water that provides public drinking water or that is available for public use. You can also capture and reuse the discharge from an aerobic system to flush toilets or for irrigation.


Aerobic septic systems require electricity to run the aerating compressor and pump, resulting in higher electricity costs for these systems than with traditional septic systems. The inclusion of these mechanical parts in the aerobic system increases the chance of problems that must be repaired, and also increases the frequency of septic system maintenance.


You can purchase an aerobic septic tank system in its entirety, or you may be able to retrofit your existing septic tank with an aerating compressor and pump. Inspectapedia advises that you seek expert advice on retrofitting an existing septic system to avoid having unprocessed solids pumped out of the tank, which can can clog the drainfield or cause sanitation problems.