The inflow to a catch basin does not all enter the basin. The flow that actually enters the basin is referred to as its "capture."

A catch basin may:

• Capture all the flow that comes to it, which is referred to as "full capture."
• Capture all of the flow up to a "maximum capacity," and you specify the maximum flow.
• Capture flow in accordance with some curve called an inflow vs. capture curve. For more information on inflow vs. capture curves, see "Adding Inflow vs. Capture Data to a Catch Basin" .
• When "Inlet Type" is set to "Catalog Inlet", with the Inlet attribute you can select a Catalog Inlet reference. By referencing a catalog inlet, the capture is computed instead of defined by the user. For more information on Catalog Inlets see Inlet Catalog Dialog Box.
• Capture a percentage of flow that comes to it, which is referred to as "percent capture”.

Any inflow that is not captured goes to a gutter. If there is no gutter, the inflow that is not captured is lost from the system.