What are the limitations of importing/exporting EPANET files?

Product(s): WaterCAD, WaterGEMS
Version(s): CONNECT Edition, V8i
Area:  Layout and Data Input

When we do an import/export with EPANET files the only data that will be retained or unaltered is the data that is supported in both EPANET INP format and WaterGEMS or WaterCAD.


WaterCAD / WaterGEMS exports the EPANET files into .INP file formats. However if you are looking a way to export them as .NET file formats of EPANET then you need to open the .INP files exported from WaterCAD / WaterGEMS into EPANET and export them from EPANET into .NET formats.

Similarly, WaterCAD / WaterGEMS import EPANET models in INP format, so if you have a model in .net format, you will need to first open it in EPANET (free download) then go to File > Export > Network to save to .INP format.

Items in WaterGEMS and WaterCAD that are not supported in EPANET:

  • VSPs
  • VSPBs
  • Fire Flow
  • Flushing
  • Pressure Dependent Demands
  • Variable reporting time steps
  • Demand/Roughness Adjustments
  • Continuous patterns
  • Elements like Hydropneumatic tanks, air valves, etc.
  • Top-filling options for a tank
  • All HAMMER (transient simulation) properties
  • User data Extensions
  • Energy costs
  • All presentation settings
  • Isolating valves/criticality
  • All ModelBuilder, LoadBuilder, Darwin, TRex and Skelebrator settings
  • Spot-elevations
  • Isolation Valves
  • Pump curves (EPANET exporter generates a CURVE.  However such curves are always imported back - during round-trips - as multi-point pump definition.  So if the original pump-definition was a 1-point or 3-point curve the round-trip may not come back to the exact original pump definition type.)
  • Unit Demands
  • Selection Sets
  • Queries
  • Graphs
  • Data from extensions (Calibrator/Designer/Capital-cost)
  • Customer meters
  • Tap/Laterals
  • Scenarios and Alternatives - EPANET does not support scenarios. So, when exporting to EPANET ensure that you have the correct scenario set to current before exporting. See more details in this article.

The expected behavior for EPANET Import is that it always creates a new model (.wtg).  In order to import the EPANET data into an existing model, the following workaround should be used:

One other thing that happens when importing EPANET files is that two extra pipes are added for every directed node.  They are labeled as something similar to "was added during EPANET import".  So when the WaterGEMS or WaterCAD model thus created is exported back to EPANET those extra pipes are removed and the original directed node is rebuilt without the extra pipes.

Hydropneumatic Tanks

Note that there is a known issue in version (defect # 526919) whereby a model with an active hydropneumatic tank will cause a "object reference not set to an instance of an object" error when attempting to export to EPANET. EPANET does not have this element so the export does not support it as noted above. Future versions will handle this situation better but in the meantime, remove the element or convert into an equivalent regular tank element in order to export.


When exporting to EPANET, only the controls that are included in the current scenario's control set (selected in the Operational alternative) will be exported. If you have controls on inactive elements (which generate a user notification in WaterCAD/WaterGEMS "Reference a deleted or inactive action element"), be sure to exclude them from the control set before exporting, to prevent error messages when opening the INP file in EPANET (such as "Input Error 204: undefined link in following line of Rule 12345". See more here: Using Controls, Conditions, Actions and Control Sets in WaterGEMS and WaterCAD

Pumps and Valves

Pumps and valves are seen as link elements in EPANET, whereas WaterCAD and WaterGEMS see them as nodes. Therefore on export to EPANET, a new link element must be created to use as the pump/valve. To do that, two overlapping junctions are created to connect to it. The link in EPANET will have the same name as the pump/valve did in WaterCAD or WaterGEMS. In EPANET, an icon will display for the pump and valve, but when trying to double-click on it, the junction could be selected by mistake.

For Example, take a look the following valve in WaterGEMS/WaterCAD:

Here's what it looks like after exporting to and opening in EPANET:

When hovering the mouse over, it may look as if it's a junction:

However if you click and drag, you'll see its actually two junctions overlapping (at the original location of the valve in WaterGEMS/WaterCAD) with the PRV link element between them:


  • The extra pipes created on either side of the valve/pump will have a very large diameter (99 inches or 2,514.6 mm) and short (near-zero) length so that no additional headloss is introduced. So, the hydraulic results should not be impacted and should match EPANET
  • For a pump, the elevation of the pump and adjacent newly created junction nodes should also not impact the hydraulics. The hydraulic grade will remain the same and the only impact of the elevation would be on the calculated pressure. For a valve such as a PRV, you may need to check the elevations if the PRV is using a pressure setting, since the pressure is calculated based on the elevation and the HGL.

See Also

Combining models with Submodel Import

Troubleshooting problems with importing EPANET or EPASWMM files

Should the EPANET solver and the WaterGEMS solver give the same results for a model?

How are units handled when exporting a WaterGEMS/WaterCAD model to an EPANET model (.inp)?

What are the difference between WaterGEMS/CAD and EPANET?