Drain line height too high?
Counter installers ran very late. New sink is installed, but it is a very large sink and sits 3+" lower than old sink. As a result the line coming out from the disposal is lower than the drain line connecting through the back wall. To make the connections the line will have at least one more 90 elbow and water will have to push up to drain.
Is this going to work? I can't get inside the wall and under the house to rerun the main drain line.