I am in the process of building an addition to my house and will be adding a bathroom. Because of the layout, the main drain from the bathroom addition exits the house and connects to the main drain from the house just prior to my septic tank. I was thinking of using an AAV for the bathroom to eliminate putting a vent through the roof - but not sure if this is possible. My understanding is that if you use an AAV, there still must be at least one vent to outside air. Given that my bathroom addition ties into my house's drain at the septic tank and not within the house - does this satisfy that requirement? or because it ties in after the house's main vent, would an AAV not work in this situation?