Mike,
Follow the steps mentioned below:
-Add the Sewer Line Feature class in ArcMap
-Right click on Sewer Line feature class and open "Layer Properties"
-Select the "Symbology" tab
-Click on the symbol
-Click on "Style References" and scroll down and check "Caves" and hit "OK"
-Scroll down to select "Water,Flow" symbol in "Symbol Selector"
- Select "Water,Flow" and hit "OK"
Hope this helps!
Regards,