What are the limitations of importing/exporting EPANET files?

Product(s):WaterCAD, WaterGEMS, HAMMER
Version(s):08.11.XX.XX and higher


When performing an import or export of EPANET files (INP) the only data that will be retained or unaltered is the data that is supported in both EPANET INP format and WaterGEMS or WaterCAD.

Note: the EPANET 2.2 INP file format is supported (import and export) starting with WaterGEMS, WaterCAD and HAMMER 2023.

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

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:

  1. Import EPANET into new model
  2. Save it
  3. Set up all the scenarios and alternatives to match the existing model
  4. Relabel to make sure labels are unique
  5. Save the model
  6. Then import it as a submodel into the existing model

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.

A Note on .NET files:

A note on EPANET 2.2

The EPANET 2.2 INP file format is supported (import and export) starting with WaterGEMS, WaterCAD and HAMMER 2023.

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:


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?