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I am trying to identify the flow path of a wastewater system.

I am using Arcgis 10.3 and I have set up a geometric network system and identified the sources and the sink (sources = blue dots, sink = green dot). The network is definitely connected as the below picture showing the result of a "find Connected" Analysis shows.

enter image description here

I have used the Set Flow Direction on the Utility Network Analyst toolbar but it is showing the flow of every pipe as indeterminate flow. I have also tried the ArcToolbox geoprocessing tool called Set Flow Direction but this hasn't changed the results. Here is what I would expect the flow to look like (sorry about my poor arrow drawing abilities). enter image description here

Is there a step that I have missed or should I be creating this network a different way?

I understand that the tool with have issues determining flow within loops. Is there some way that I could integrate a contour layer to assist in flow direction?

This is just a small portion of several networks I have, hence I need an automated solution.

  • Have you tried selecting a few of your lines and clicking the Connect button on the Geometric Network Editing toolbar, and then trying to set flow direction? – Midavalo Apr 4 '16 at 1:47
  • I have tried using the flag tool to see if I can find the path upstream/downstream. But this has no results. – N. Begg Apr 4 '16 at 2:02
  • That won't work until you've established flow direction. – Midavalo Apr 4 '16 at 2:04
  • It may be total overkill for this project, but if water network tracing is a large part of your business you could look at ArcFM, which is a utility-specific solution built on top of ArcGIS. In particular their water tracing algorithms and functionality are much more advanced than standard ArcMap – Stephen Lead Apr 4 '16 at 3:20
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There is a button on the Utility Network Analyst toolbar (the same one you run your trace from) called Set Flow Direction. You need to use that to establish/calculate your flow direction before you can use the direction trace tools.

enter image description here

  1. Click the Editor menu on the Editor toolbar and click Start Editing.
  2. Click the Set Flow DirectionSet Flow Direction button on the Utility
  3. Network Analyst toolbar. This sets the correct flow direction for your network.
  4. Click the Editor menu on the Editor toolbar and click Stop Editing.
  5. Click Yes to save your changes.

(from Setting the flow direction - ArcGIS Desktop Help)

There is also an ArcToolbox geoprocessing tool called Set Flow Direction that will do it, under Data Management > Geometric Networks. This can be used to set the flow direction based on different factors - source/sink, digitised direction, against digitised direction.

It may be an option to set flow by digitised direction rather than source/sink to help overcome your flow through loops issue. We don't use source/sink for our networks, we only use digitised flow direction.


Digitised Flow Direction means that the geometric network uses the direction you have drawn the lines in your GIS as the direction of flow. So if you start drawing your line at Manhole A and finish your line at Manhole B, then your flow will be Manhole A to Manhole B. To use this on an established dataset means you would need to ensure every line was drawn in the direction of flow.


Check that your lines are actually connected in your geometric network. To do this, start editing and select a handful of lines (to test) and click the Connect button on the Geometric Network Editing toolbar (this is different to the Utility Network Analyst toolbar you use for tracing).

enter image description here

Once they are connected, try the Set Flow Direction button again and see if the lines you just connected now have flow direction set.


Also, check out Esri's Water Utility Network Editing and Analysis Tools. This features a couple of new toolbars that will help you set up your geometric network and with future editing and tracing. One of the tools will even flip your line digitised directions to match the flow direction so that everything is the right way, although this does require flow direction to be set first. My team uses these tools all day every day.

  • Sorry for the unclear question - I am just new to all of this. I have edited my original question to show that I had already gone through the above process of setting the flow direction that you have suggested. – N. Begg Apr 4 '16 at 1:39
  • Can you please tell me more about the digitising flow direction process? – N. Begg Apr 4 '16 at 1:40
  • Have added a brief description on how the Digitised Flow Direction works – Midavalo Apr 4 '16 at 1:48
  • Thanks. Digitised Flow Direction would be the way to go if I was working on a small dataset but unfortunately I have approximately 500km of wastewater lines and part of the point of this exercise is to identify the direction of flow. – N. Begg Apr 4 '16 at 1:59
  • have added info about connecting features in the network – Midavalo Apr 4 '16 at 2:13

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