Pick HydroCAD if
You live in a routing diagram and you do not need the drawing to stay in lockstep. It is cheap and known.
Compare
Same job. Different desks.
Public list prices as of 2026. Features are the common case, not every add-on. StormDesigner Release 1 is DA, ditches, pipes, report, plus hydrograph and pipe-network layout. Full hydro Run and HGL are later.
| StormDesigner | HydroCAD | Hydraflow Storm Sewers | Bentley OpenFlows Storm | Autodesk InfoDrainage | |
|---|---|---|---|---|---|
| Where it lives | Exe next to Civil 3D. Named pipe. | Standalone. Import / export. | Civil 3D extension. | Standalone + Bentley CAD. | Standalone. Round-trip to Civil 3D. |
| Project file | .sdp with cached rings | .hcp | .stm + DWG | Bentley model | InfoDrainage + DWG |
| Online USDA soils | Yes | No | No | GIS import | GIS / mapping |
| NOAA Atlas 14 | Yes, in the .sdp | Rainfall library | IDF you load | Yes | Yes |
| PRE / POST drainage areas | Release 1 | Subcatchments | Inlets, not DA overlay | Yes | Catchments |
| Ditch / swale calc | Release 1 | Reaches | Pipes | Channels | Yes |
| Single pipe calc | Release 1 | Culverts / reaches | Network | Yes | Yes |
| Pipe network HGL / EGL | Layout now. HGL Run later | Not the point | Yes | Yes | Yes |
| Hydrographs / ponds | Nodes now. Run later | Core product | No | PondPack in the suite | Yes |
| Water quality | Coming soon (NCDEQ) | Pollutant loading | No | Varies by tier | SuDS / SCM |
| Calculation report | Vector PDF in the .sdp | Built-in | Print / export | Yes | Templated |
| List price (about) | $695 / year / seat | From $195 / year or $295 forever | With Civil 3D | From $1,355 / year | Autodesk subscription |
HydroCAD 20-node annual is often $375. Bentley OpenFlows Storm Essentials lists $1,355 for 12 months. Civil 3D already sits on most of our users' machines. StormDesigner does not replace Civil 3D. It does not try to be a city-wide 2D flood model.
Pick Bentley or InfoDrainage if
You model large networks, 1D/2D flooding, or you already bought that stack.
Pick StormDesigner if
You design sites in Civil 3D and you want soils, rain, DAs, ditches, pipes, and a report without leaving that job.