Placing Downspout Connections
Downspout connections document where a building's roof drainage — carried down by gutters and downspouts — enters the underground site drainage network.
Downspout ConnectionThe Downspout object marks where a gutter downpipe ties into the ground-level drainage network. Place one at the base of each downspout, then record the connection Diameter (mm) and any installation Notes in the Inspector. Connect it onward with a drain pipe to a catch basin or outlet so the network accounts for the roof contribution.
Activate the Downspout Connection tool
In Drainage mode, select the Downspout Connection tool from the toolbar or component palette. The cursor changes to a placement crosshair ready to place the component on the canvas.
Click at the base of each downspout
Click on the canvas at the base of each downspout location — near the building corner or along the wall face where the downspout terminates. The component appears as a small symbol on the 2D plan indicating a drainage entry point. Place one component per downspout.
Connect to the drain pipe network
Switch to the Draw Pipe tool. Start a pipe run at the downspout connection component and route it toward a catch basin or directly to an outlet. If multiple downspout connections are close together, you can route individual short pipes from each connection to a shared catch basin, then run a single outgoing pipe from the basin to the outlet.
Set burial depth for the connecting pipe
Select the pipe drawn from the downspout connection and set the burial depth in the Inspector. The connection point itself is typically at or near the surface. The connecting pipe transitions to a buried run once it leaves the building wall. Ensure the burial depth is sufficient to maintain a downhill gradient toward the outlet.
Connect with a drain pipe
Place a Drain Pipe from the Conveyance & Discharge section, click the downspout connection to start the run, then route it to the nearest catch basin or onward toward the drainage outlet. Set the pipe Diameter in the Inspector to match the discharge size.
Route to a soakaway or outlet
If local regulations permit infiltration, route the downspout pipe to an Outlet configured as a Soakaway to handle roof runoff separately from the surface network. Otherwise connect it to a catch basin that feeds the main run.
Roof runoff from a large building can carry significantly more volume than surface water from the same footprint, especially in heavy rain. Size the connecting pipe and receiving basin for the combined load, or route downspouts to a dedicated soakaway to reduce peak discharge.
Use a consistent naming convention for downspout connections, such as 'DS-01', 'DS-02', and so on. This makes them easy to cross-reference in cost estimates and drainage schedules.
Frequently Asked Questions
Is there a dedicated downspout object?
Yes. The Downspout object lives in the Water tab under Surface Collection. Place one at the base of each downspout and set its diameter and notes in the Inspector.
How do I set the connection diameter?
Select the placed downspout connection and open its Downspout Connection section in the Inspector. Enter the Diameter (mm) to match the downspout discharge pipe.
Can I connect a downspout directly to a catch basin?
Yes. If the downpipe enters a catch basin lid directly, place the catch basin at that location and connect the downspout object to it with a drain pipe.
How do I show downspout connections on a printed plan?
Placed water objects appear on the layer you draw them on and are included in 2D plan exports. Name each connection clearly so it reads on the printed sheet.