How Household Septic Tanks With Two Chambers Work

The majority of residential septic tanks have a single chamber into which all of the waste products and water are emptied. In certain applications, a dual chamber septic tank is required. These are most commonly used when a septic tank pump is being used.


Bacteria present in the waste products thrives in the low oxygen environment of the septic tank.  This bacteria feeds on the waste material and will eventually break it down into a liquid state. This liquid can then be piped to the field lines where it is absorbed into the soil. 

Two Chambers

Until the waste material is broken down, it can cause a sludge buildup.  This sludge buildup can also be caused by other items entering the tank, such as from a garbage disposal, which should not be used with a septic system. This sludge can build up and clog the pumping unit if not kept in a separate chamber until broken down. 

How It Works

A baffle wall separates the two chambers inside the tank.  As the bacteria break down the waste, the resulting liquid flows over the baffle wall and into the second chamber containing the pumping unit. The liquid can then be pumped out while the unprocessed sludge/waste remains in the first compartment. 

About the Author

Tom Raley is a freelance writer living in central Arkansas. He has been writing for more than 20 years and his short stories and articles have appeared in more than 25 different publications including P.I. Magazine, Pulsar and Writer's Digest.