Rule 15-18-77-5.2.4 - Inlet and Outlet1. The inlet and outlet must be schedule forty (40) pipe four (4) inches in diameter. A three (3) inch house sewer stubout, when used, shall be connected to the four (4) inch pipe from the septic tank inlet using manufactured fittings designed for that purpose.2. The inlet and outlet pipe (schedule 40 four (4) inch) must extend a minimum of three (3) feet onto undisturbed soil before entering and after exiting the Advanced Treatment System.15 Miss. Code. R. 18-77-5.2.4