SWMM 5 reference manual - still a work in progress
The previous thread on the list inquired about a full reference manual for SWMM 5 that would explain all of the equations and solution methods it uses. Such a manual has been "in preparation" for several years now, starting with several chapters on hydrology written under contract by Wayne Huber, but it keeps getting pushed aside by other higher priority activities. There is no extramural money available at EPA for this task, nor any "team" besides myself to work on it. Never fear though, it will get done at some point in time, hopefully before I retire (or someone writes a SWMM 6).
Don't forget about the SWMM applications manual. It doesn't have the equations that SWMM runs on, but it can be helpful with applications.