Also known as
Model type Single
Model part of larger framework
Note on status model
Date note status model
Incorporated models or components:
Spatial dimensions 2D
Spatial extent Landscape-Scale, Watershed-Scale, Reach-Scale
Model domain Hydrology, Terrestrial
One-line model description Storm Water Management Model
Extended model description The EPA Storm Water Management Model (SWMM) is a dynamic rainfall-runoff simulation model used for single event or long-term (continuous) simulation of runoff quantity and quality from primarily urban areas. The runoff component of SWMM operates on a collection of subcatchment areas that receive precipitation and generate runoff and pollutant loads. The routing portion of SWMM transports this runoff through a system of pipes, channels, storage/treatment devices, pumps, and regulators. SWMM tracks the quantity and quality of runoff generated within each subcatchment, and the flow rate, flow depth, and quality of water in each pipe and channel during a simulation period comprised of multiple time steps.


Name Lewis Rossman
Type of contact Project manager
Institute / Organization U.S. Environmental Protection Agency (EPA), Ground Water and Ecosystems Restoration Division
Postal address 1 P.O. Box 1198
Postal address 2
Town / City Ada
Postal code 74821-1198
State Oklahoma
Country United States
Email address
Phone (580) 436-8500

Supported platforms
Other platform
Programming language

Other program language
Code optimized Single Processor
Multiple processors implemented
Nr of distributed processors
Nr of shared processors
Start year development 1971
Does model development still take place? Yes
If above answer is no, provide end year model development
Code development status
When did you indicate the 'code development status'?
Model availability As code
Source code availability
(Or provide future intension)
Through web repository
Source web address
Source csdms web address
Program license type Other
Program license type other --
Memory requirements --
Typical run time --

Describe input parameters --
Input format
Other input format
Describe output parameters In addition to modeling the generation and transport of runoff flows, SWMM can also estimate the production of pollutant loads associated with this runoff. The following processes can be modeled for any number of user-defined water quality constituents:
  • dry-weather pollutant buildup over different land uses
  • pollutant washoff from specific land uses during storm events
  • direct contribution of rainfall deposition
  • reduction in dry-weather buildup due to street cleaning
  • reduction in washoff load due to BMPs
  • entry of dry weather sanitary flows and user-specified external inflows at any point in the drainage system
  • routing of water quality constituents through the drainage system
  • reduction in constituent concentration through treatment in storage units or by natural processes in pipes and channels
Output format
Other output format
Pre-processing software needed? No
Describe pre-processing software
Post-processing software needed? No
Describe post-processing software
Visualization software needed? No
If above answer is yes
Other visualization software

Describe processes represented by the model SWMM accounts for various hydrologic processes that produce runoff from urban areas. These include:
  • time-varying rainfall
  • evaporation of standing surface water
  • snow accumulation and melting
  • rainfall interception from depression storage
  • infiltration of rainfall into unsaturated soil layers
  • percolation of infiltrated water into groundwater layers
  • interflow between groundwater and the drainage system
  • nonlinear reservoir routing of overland flow.
Describe key physical parameters and equations SWMM conceptualizes a drainage system as a series of water and material flows between several major environmental compartments. These compartments and the SWMM objects they contain include:
  • The Atmosphere compartment, from which precipitation falls and pollutants are deposited onto the land surface compartment. SWMM uses Rain Gage objects to

represent rainfall inputs to the system.

  • The Land Surface compartment, which is represented through one or more Subcatchment objects. It receives precipitation from the Atmospheric compartment in the form of rain or snow; it sends outflow in the form of infiltration to the Groundwater compartment and also as surface runoff and pollutant loadings to the Transport compartment.
  • The Groundwater compartment receives infiltration from the Land Surface compartment and transfers a portion of this inflow to the Transport compartment. This compartment is modeled using Aquifer objects.
  • The Transport compartment contains a network of conveyance elements (channels, pipes, pumps, and regulators) and storage/treatment units that transport water to outfalls or to treatment facilities. Inflows to this compartment can come from surface runoff, groundwater interflow, sanitary dry weather flow, or from user-defined hydrographs. The components of the Transport compartment are modeled with Node and Link objects.

Not all compartments need appear in a particular SWMM model. For example, one could model just the transport compartment, using pre-defined hydrographs as inputs.

Describe length scale and resolution constraints --
Describe time scale and resolution constraints --
Describe any numerical limitations and issues --

Describe available calibration data sets
Upload calibration data sets if available:
Describe available test data sets
Upload test data sets if available:
Describe ideal data for testing

Do you have current or future plans for collaborating with other researchers? Since its inception, SWMM has been used in thousands of sewer and stormwater studies throughout the world. Typical applications include:
  • design and sizing of drainage system components for flood control
  • sizing of detention facilities and their appurtenances for flood control and water quality protection
  • flood plain mapping of natural channel systems (SWMM 5 is a FEMA-approved model for NFPI studies)
  • designing control strategies for minimizing combined sewer overflows
  • evaluating the impact of inflow and infiltration on sanitary sewer overflows
  • generating non-point source pollutant loadings for waste load allocation studies
  • evaluating the effectiveness of BMPs for reducing wet weather pollutant loadings.
Is there a manual available? Yes
Upload manual if available: Media:Epaswmm5 user manual.pdf
Model website if any
Model forum / discussion board There is no formal support offered for EPA SWMM. A SWMM Users Listserve, established by the University of Guelph, allows subscribers to ask questions and exchange information. To subscribe, send an email message to with the words "subscribe swmm-users" (without the quotes) in the body followed by your name.
Comments Model questionnaire filled out based on website, by Albert Kettner

This part will be filled out by CSDMS staff

OpenMI compliant No but possible
BMI compliant No but possible
WMT component No but possible
PyMT component
Is this a data component
Can be coupled with:
Model info
Lewis Rossman
Nr. of publications: 157
Total citations: 2594
h-index: 26
m-quotient: 0.52
Qrcode SWMM.png
Link to this page




Nr. of publications: 157
Total citations: 2594
h-index: 26
m-quotient: 0.52

Featured publication(s)YearModel describedType of ReferenceCitations
Rossman, L.A.; 2006. Storm Water Management Model Quality Assurance Report: Dynamic Wave Flow Routing.. EPA/600/R-06/097.
(View/edit entry)
2006 SWMM

Model overview

Rossman, L.A.; 2010. Storm Water Management Model User’s Manual Version 5.0.. EPA/600/R-05/040.
(View/edit entry)
2010 SWMM

Model overview

See more publications of SWMM



Input Files

Output Files