Originally Posted by BFlinn181
I think that vent is to equalize pressures so you maintain water in drain traps and exhaust methane build up, it doesn't really supply oxygen to the septic tank.
Prolly true.. depends on the the setup.. Mine at the Duplex just had new output baffles installed, but the input pipe is above the waterline and is vented. While its not an aeration pump as tinker was saying, its certainly not a 'closed system'. Also as tinker mused, septic systems are prolly a little different depending on where you are and the soil conditions. I know in Wisconsin, my buddy had a mound system with aeration pump and the type I have is not allowed.