How to put a background from AutoCAD into SWMMM or EPANET

See also some tips for each program at the bottom of this post.

In AUTOCAD

1. In model space, set up the view you want to use as your backdrop. Put a box around it and note the corner coordinates for future use (below).
2. Go to tilemode 0 (a Layout).
3. Set up an mview using the coordinates from step 1 and zoom it to the same coordinates, which will make its zoom factor 1.
4. Option A. With MSPACE active inside the mview viewport, export (WMFOUT) ALL objects as a WMF file.
 Option B. In paper space, plot to PNG using a custom paper size with dimensions some proportion of the viewport size (Try to estimate how many pixels per foot (unit) will look good on your background image).  Then use Windows Paint or some other program to save the PNG file as a BMP file.

In EPANET or SWMM

Backdrop

Use View, Dimensions to set the the right units and the corner map coordinates to what you noted above.
Use View, Backdrop, Load... to load the WMFOUT or BMP file you created in AutoCAD
Check the approximate coordinates of couple of known points on the backdrop.

Additional tips for EPANET only

Settings
File, Preferences, Formats to set units to 0 places.
Project, Defaults, Propertes to turn Auto Length ON. Also check default elevation, size, roughness (150 for PVC), and ID Label prefixes.

Network
Use circle Junction icon on toolbar to add junctions at all important intersections and ends. Consult another engineer to make model appropriately simple.
Use Pipe icon on toolbar to add pipes between junctions. Hold down CTRL key to follow bends.
Use Reservoir icon on toolbar to add the water system as a source of water with its total head at ground level.
Find the Browser pane and under Data, choose Curves and pick the Add icon below to add a one or three point curve to describe the system supply curve. (Head = Pressure * 2.3 and Pressure = Head * 0.4333)
Use Pump icon to connect the reservoir to your network with the system supply curve you defined.
Double-click pipes (links) and junctions to edit sizes and elevations.
Add demands at one or some some of your junctions, then Project, Run analysis.

Results
In Browser pane (window), Map tab, select something to show on nodes and links.
Under View, Options, change the sizes of text and objects on the map.
Get a table under Report, Table.
Export a summary report from Report, Full, to a file, and then view or print it.

Additional tips for SWMM only

Settings
File, Preferences, Formats to set Flow units to 0 places.
Right-click on Auto-Length in the Status Bar to turn Auto Length ON or OFF.