In the Workspace section, you can change the symbols used, text content, and location of the text on the Workspace. Note that all display changes are made only for the user's convenience/preference and do not affect the model calculations. Additionally, many display options available in the User Options window are also available in individual pipes and junctions.


A traditional 2-D grid or an Isometric grid can be displayed on the workspace for modeling convenience based on the Pipe Drawing Mode that is selected. The number of lines in the grid can be adjusted to create a grid that is fine, medium or coarse. The grid can be hidden or shown by checking or unchecking the Show Grid box accordingly. If the grid is shown, the grid line pattern can be solid or dashed. The pipes and junctions can also be snapped to the grid, which moves junctions and pipe end points to the closest intersection of grid lines.

The Pipe Drawing Mode and the toggle to Show Grid can also be found on the Arrange menu.


The display of pipe lines, closed pipes, pipe endpoints, and pipe direction arrows can be adjusted according to your preferences here.

Pipe line thickness can be adjusted from 1 to 10 pixels by selecting the desired pixel value in the box next to Pipe Line Thickness (pixels). You may choose to show all pipes as having the same thickness, or you can vary the thickness with an increasing pipe diameter. If varying the thickness according to the pipe diameter, you can allow Fathom to vary the thickness in a gradual fashion with larger diameters shown as having increasingly larger thicknesses, or you can customize two diameters between which the thickness will vary. In the latter case, any pipes with diameters below this minimum value will have the pipe thickness of the minimum diameter pipe, and any pipes with diameters above this maximum value will have the pipe thickness of the maximum diameter pipe. To customize the pipe thickness variation, input the minimum and maximum diameter between which you wish the pipe thickness to vary, as well as the pipe thickness that will represent the minimum diameter pipe and the pipe thickness that will represent the maximum diameter pipe. The pipe thickness will vary in a linear fashion between the two diameters specified.

You can close a pipe using the Special Conditions feature which closes the pipe to flow at both ends. From the User Options window, you can select how you would like a closed pipe to be displayed in the workspace. The options include a solid line, dashed line, a dotted line, and dashed-dotted combinations.

When building a model, Fathom automatically adjusts pipe endpoints to the centers of junctions for user convenience. If you would like to disable this feature, uncheck the box next to Automatically Adjust Pipe Endpoints to Junction Centers in the Pipes window.

The Pipes window in User Options also allows you to adjust the display of flow direction arrows on the pipes. Under the Pipe Direction Arrows section of the Pipes window, you can select the size of arrow you would like to be displayed as a percentage of the pipe thickness. Additionally, you can opt to not show a pipe direction arrow by checking the option Do Not Show Arrow.

Note: The pipe direction arrow is used as a reference direction for flow and does not change direction on the workspace if the calculated flow is in the opposite direction indicated by the arrow. Instead, the flow is reported as a negative flow in the output.


The junction icon style displayed on the Workspace can be chosen in Junctions underneath the Workspace section in the User Options window. The two available icon styles include classic icons and transparent icon. Classic icons are the icons used in earlier versions of Fathom ending at Version 7 in which each junction is surrounded by a box, and transparent icons are updated icons not surrounded by boxes.

You can also select the icon size and label location for junctions. To adjust the size, click on the box below Icon Size in the Junctions window and choose the percentage of the default size that you would like the junction icons to be sized. For the junction label location, you can select from any of the eight locations shown in the window by clicking on the selection circle that corresponds to the desired location.

Note: Junction and pipe labels can be moved individually on the Workspace by using the mouse to drag and drop the label according to your preferences.

The final option in the Junctions window of the User Options is to enable or disable a dotted outline around a closed junction. If this option is enabled, a dotted box will appear around the junction when it is closed with Special Conditions. If this option is disabled, no dotted box will appear.


Display settings for pipe and junction labels on the Workspace can be customized under Labels in the Workspace section of the User Options window. When a pipe or junction is inserted onto the Workspace, the next whole number available at the increment specified in this window is automatically assigned to the new pipe and/or junction. Fathom's default is to increment pipe and junction numbers by one. Therefore, the first pipe you place on the Workspace will automatically be labeled as Pipe 1 (P1 for brevity), the second will automatically be labeled P2, etc. Junctions are labeled in a similar fashion with a "J" in front of the number to indicate it is a junction. However, if you choose a different increment in the User Options window for pipes and/or junctions, the automatic numbering will increment pipes and/or junctions according to the specified number. You can renumber any pipe or junction individually as long as the number is not already used in any scenario of the model. If a number at the increment is already in use, Fathom will skip to the next available whole number. Pipe and Junction label numbers are limited to integers between 0 and 99,999.

Note: A unique label must exist for each pipe and junction on the Workspace. Therefore, there cannot be more than one P1 in the model, but a P1 and J1 can exist simultaneously because the leading letter is different.

Additionally in this section in the User Options window, you can select if you would like the pipe and/or junction numbers only to be displayed, if you would like the names only to be displayed, or if you would like both the name and number to be displayed. To choose which display option you would like, select the radio button next to the desired display option under Pipe/Junction Default Display.

Note: If you would like a pipe and/or junction display label type to vary from the default option selected in Labels in the User Options window, you may choose the display label type for individual pipes and junctions in the Optional tab of the individual pipe or junction properties window under Display on Workspace.

You can also choose whether the pipe and junction labels should be moveable at all times, or if they should only be moveable when the user is holding down the shift key. Select which option you prefer by clicking on the radio button next to your preference. Restricting the movement of labels can be especially helpful to users with complicated or dense models, as it is possible to inadvertently grab a label when attempting to reposition or select an icon on the Workspace.

Colors and Fonts

The Colors and Fonts window located under the Workspace section in the User Options window allows you to change the colors of the following parameters seen on the Workspace:

  • Pipe and Junction Symbols

  • Junction Numbers

  • Pipe Numbers

  • Pipes

  • Selected Items

  • Undefined Numbers

  • Workspace Background Base Scenario

  • Workspace Background Children

  • Workspace Background Grandchildren

  • Workspace Background 3rd Generation

  • Workspace Background 4th Generation +

  • Grid

The currently selected color for each parameter is shown to the right of the parameter. To change the color for any parameter, either select the box containing the parameter's color and then click on the Set Color box under the list, double click on the box containing the color you would like to change, or click the "..." button next to the color of the parameter you would like to change. A color window pops up that allows you to choose from 48 basic colors, or to create a custom color by clicking anywhere in the color box and adjusting the slider at the right of the box to create the color of your choice. If you would like to save the custom color for use in other areas of the model, click on any empty box underneath Custom colors: and then click on the Add to Custom Colors box below the color box. When finished with selecting a color, click OK on the bottom left of the Color window.

If you would like the background color of the children and grandchildren scenarios to maintain the same color as the base scenario, click on the Set All Background Colors to Base Color button under the Parameter/Color list.

You may also choose to change the font of all junction and pipe names and numbers by clicking on the Change Font button to the right of the Font for Junction and Pipe Numbers on the Colors and Fonts box in the Workspace section. A preview of the current font is given underneath the Font for Junction and Pipe Numbers title.


Symbols representing pipe or junction special conditions and inflow or outflow are listed in the Other window under the Workspace section in the User Options window. These symbols can be disabled by unchecking the box on the left of the list. User's can also change what symbol will be used by clicking in the Symbol box on the right and typing the new desired symbol.

If you choose to include a background picture in your model, you can adjust the picture size in this section, as well. To scale a background picture, enter a Scale Multiplier in the box underneath Background Picture Scaling.