I am sure you have come across a threaded sewer connection that is mounted in a recessed concrete pad. The recess allows for drainage into the sewer. The problem, that I haven't been able to figure out, is screwing my 90-degree fitting into the sewer connection. Some of the recesses are deep enough that you cannot connect the hose bayonet to the 90-degree fitting. I haven't been able to find a 45-degree fitting with threaded end, which likely would work. I have tried using the 90-degree with the flexible rubber seal to add a little elevation, but it is not as tight as screwing in the fitting.

Any thoughts on this?