Recent Examples on the WebThese pipes connect to what's called a soil pipe, also known as a discharge pipe, which washes the waste away from the toilet, sink or drain. Helen Regan, CNN, 12 Feb. 2020 The soil pipe needs to have a vent pipe connected, which ensures the sewer gases and odors are carried away -- usually through a vent in the roof. Helen Regan, CNN, 12 Feb. 2020