Drawing Drain Pipes
Drain pipes carry collected surface water through the drainage network. Use the Draw Pipe tool in Drainage mode to connect inlets, catch basins, and outlets.
Drawing Drain PipesThe Drain Pipe object draws the pipe runs that link your drainage objects — inlets, catch basins, channel drains, and outlet points — into a connected system. You control the pipe diameter, the burial mode and depth, and an optional fall (slope) from start to end so water drains in the direction you intend. A computed slope percentage in the Inspector helps you confirm the run falls toward the outlet.
Click to start and add waypoints
Click on the canvas at the starting point — typically a drain inlet or catch basin. Continue clicking to add waypoints wherever the pipe changes direction. Each click adds a new node to the pipe path. The pipe preview follows the cursor as you move between clicks.
If no drainage objects are placed yet, add at least one inlet or catch basin first so you have endpoints to draw between.
Finish the pipe run
Double-click the final point, or click on the target component and press Enter, to complete the pipe. If the endpoint is near a drain inlet, catch basin, or outlet, it snaps to that component's connection point, creating a logical link in the drainage network.
Set pipe diameter in the Inspector
Select the completed pipe to open the Inspector. Set diameterMm to the appropriate size for the anticipated flow. Common residential sizes are 100 mm (light duty, short runs), 150 mm (medium runs and patios), and 200 mm (high flow or long runs). The diameter is used in flow calculations and appears in plan annotations.
Configure burial depth
In the Inspector's Burial Settings section, the pipe defaults to Buried mode at 300 mm depth. Adjust depthMm to reflect the actual installation depth — for example, increase to 450 mm under a driveway. The pipe renders as a dashed line for any buried mode. See the Burial Depth article for full details on burial modes.
Enable slope for a falling pipe
Open the Slope section and tick Enable slope. Two sliders appear: Start Depth and End Depth (each 0.1–1.5 m). Set the End Depth deeper than the Start Depth so the pipe falls toward its outlet. A computed slope percentage is shown below the sliders.
Review the run length
The Pipe section shows the total run length and point count. The length feeds into cost takeoffs, so drawing at true scale keeps the quantity right.
If the End Depth is shallower than the Start Depth, the pipe runs uphill and water cannot drain by gravity. Increase the End Depth or decrease the Start Depth until the slope reads as a positive fall toward the outlet.
Diameter and burial settings apply per pipe run. To update several runs at once, select them together and change the shared properties in the multi-selection Inspector.
A minimum fall of about 1% is a common civil-engineering guideline for self-cleaning pipe flow. Confirm the required gradient with a qualified engineer for your site.
Frequently Asked Questions
What diameters are available for a drain pipe?
The Pipe section offers 75, 90, 110, 160, and 200 mm. Step up a size where a branch joins the run so downstream trunk pipes carry the combined flow.
How do I make the pipe slope downhill?
Open the Slope section, enable slope, and set the End Depth deeper than the Start Depth. The computed slope percentage confirms the fall. If it reads negative, the pipe runs uphill — adjust the depths.
How do I bury the pipe?
Open the Burial section and set the Mode to Buried. A Depth slider appears so you can set the cover depth. On Surface and Inset modes are also available.
Can I route a pipe with bends and corners?
Yes. Each click during drawing adds a waypoint, so you can jog the pipe around structures or other services. The total length shown in the Inspector accounts for all segments and feeds the cost estimate.
How do I update an entire run at once?
Select the pipe run and change its diameter or burial in the Inspector; the change applies to the whole run. To change several runs together, multi-select them and edit the shared properties.