The bacteria active in a septic tank are anaerobic. Anaerobic means the bacteria operate without oxygen from the air. ... There is not a great deal of gas generated in a septic tank, but the gas must be released so pressure does not build up in the tank. If the septic tank has inlet and outlet baffles, they must be vented.

How does a septic tank breath?

As the septic tank fills with waste and water, the air has to go somewhere or the pressure will stop the flow and back up into the structure. To solve this problem a vent is connected to the top of the tank to release the waste gases and air outside.

Why can I smell my septic outside?

A properly-maintained septic tank should be odor-free, so if you notice a bad smell inside your home or outside near the leach field, it's a sign that there's a problem. ... Septic odors are caused by gases in the system, including carbon dioxide, hydrogen sulfide, and methane.