Which year and model of 22R do you have? Since the spirit was made on a number of years and number of different models, we can't say what might be involved but I can refer you to the drawings that I consider almost a lifesaver!
https://catalog3d.winnebagoind.com/menu/Parts.htm
This will get you to the parts catalog where there are drawings of all the major parts like plumbing, electrical, etc. that you can turn and view from different angles to see details of things we could never spot by looking at the RV.
It does take a bit of "playing" to figure the controls but worth the time.
One big one is down in the lower left side, there is a "cross" + symbol which lets you pick a specific spot on the drawing when you tilt or zoom and will make that spot stay the center! Also note that the list at the right can be used to choose what part if you know the name, click on it in the list and that makes it show in yellow on the drawing! Or if you spot a part on the drawing and want to know what the name, click the drawing and it shows up on the list!
Some Spirit have drains only, some have bypass, and some have both!
Some examples of the plumbing info for drains and bypass on the various Spirit models: