From DHI web site:

MIKE URBAN combines DHI’s 20-year tradition for leadership in simulation engines with ESRI’s world leading GIS technology. The result is a tool set that defines a new industry standard in usability, productivity and pure pleasure.

Mike Urban - Water Distribution:

• EPANET Engine
• Proprietary DHI Water Hammer Engine
• Water Quality
• Advanced Rule-based Control

Mike Urban - Collection Systems:

• SWMM5 Engine
• Proprietary DHI MOUSE Engine
• Water Quality
• Advanced Rule-based Control

For more information see Mike Urban web page.