3 Key Differences Between VO SWMM and EPA SWMM

🌧️ Enhanced Urban Runoff Modelling with VO SWMM 🌧️

Term Definitions

EPA SWMM: The United States (US) Environmental Protection Agency (EPA) Storm Water Management Model (SWMM), is a dynamic rainfall-runoff simulation model used for analyzing stormwater runoff quantity and quality and sewage flows from urban areas.

VO SWMM: Integrating the US EPA SWMM computational ‘engine’ into the VO user interface. The VO user interface builds on the features and capabilities of the US EPA SWMM program interface. 


Understanding and controlling urban stormwater runoff, including managing the quantity and quality of the water produced in urban environments, has always been a challenge. The random nature of the volume, intensity, frequency, and distribution of storms and other related watershed and climatic events, makes sizing urban infrastructure difficult.

The US EPA SWMM program, first developed in the late 1960s, aimed at facilitating this understanding by using computers. VO SWMM, building upon this foundation, provides an upgraded user interface to the US EPA SWMM program along with numerous features and enhancements developed to meet relevant regulatory requirements in the US and Canada.

VO SWMM v. EPA SWMM: 3 Strengths for VO

1. Visualization:

VO SWMM has a simple and flexible interface, focusing on the conceptualization and mapping of a drainage system.

VO SWMM provides two distinct visual options for creating models: schematic view and map view. The schematic view focuses on the conceptualization of relationships within drainage systems while the map view enables users to precisely position commands in their intended locations. This feature also automates the extraction of properties for select commands, further enhancing the user experience.

Schematic view

Map view

VO SWMM stands out for its modern interface streamlining the model creation process and requiring fewer steps.

2. Easy-to-Use:

Error List

As command/object connections are made and input parameters are set, errors occur. Identifying and resolving these issues in VO SWMM models is expedited with the “Error List”. This feature prompts recognition using warning indicators such as highlighting erring commands/objects in bold red and providing a description of the issue in the bottom panel. 

EPA SWMM and VO SWMM error views

Resource Library

The built-in Resource Library allows the users to conveniently define and manage time series inputs such as precipitation (rain and snow), temperature, flows, groundwater, and evaporation inputs. Then, effortlessly export results in various formats.

3. GIS Tools:

VO SWMM’s integrated GIS Tools feature also presents a distinct advantage. The built-in GIS tool efficiently imports and exports diverse layer formats (such as DEM), establishes contour lines, clips raster data, and even automates the generation of sub-catchments. This integration of GIS capabilities significantly enhances the precision and effectiveness of your urban and rural runoff modelling.

GIS Tool Banner

GIS Map View

Subcatchment creation

Polygon creation

Download DEM

Raster to Contour


Dual-Drainage Modelling

VO SWMM has built-in capability to perform dual-drainage analysis. Dual drainage simulates flow along street, capture at catch-basins/inlets, and flow along sewer simultaneously. It incorporates tools to create the dual-drainage models quickly. This technique in VO SWMM facilitates an understanding of the interactions between capture and hydraulic gradient in sewers and even the inflow and infiltration that occurs due to overland flow over sanitary manhole covers. 


The US EPA SWMM’s open-sourced engine has provided the essential mathematical modelling foundation for other SWMM products.

Now, VO SWMM is the enhanced solution for our day, full of features and capabilities that combine a visual interface with user-friendly and convenient tools. With dual-drainage modelling, municipalities and their communities can gain critical insights into their sewer systems impacted by inflow/infiltration from overland flow.

🌧️ Experience the simplicity and power of enhanced urban runoff modelling with VO SWMM. 🏙️

To request a VO SWMM license, click HERE

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