> ## Documentation Index > Fetch the complete documentation index at: https://docs.picsy.uk/llms.txt > Use this file to discover all available pages before exploring further. # Edit a catchment > Include or exclude individual hexes and nearby built-up areas. Use catchment editing when the generated boundary needs a local adjustment. Start with the closest suitable type and range, then make only the changes you need. ## Edit individual hexes Open **Catchment settings** and select **Edit**. PICSy shows the edge hexes available to change. Catchment settings with a red circle around the Edit button.

Catchment settings with a red circle around the Edit button.

Select a green hex outside the catchment to include it. Select a red hex inside the catchment to exclude it. Select the same hex again to undo that edit. Catchment hex editing enabled, showing green hexes outside the boundary, red hexes inside it, and the Done button in Catchment settings.

Catchment hex editing enabled, showing green hexes outside the boundary, red hexes inside it, and the Done button in Catchment settings.

Select **Done** when the boundary is right. The map and analysis update as you edit. Only hexes at the edge of the catchment can be changed. ## Change built-up-area inclusion When a nearby built-up area is available, hover over it to reveal its **+** or **−** control. * select **+** to include the built-up area * select **−** to exclude it The boundary and figures update immediately. If no controls appear, there are no built-up areas available to change for the current catchment. ## Reset or save the edit * Select **Reset** in **Catchment settings** to remove every manual hex and built-up-area change. This does not change the catchment type or range. * Open **Save** and choose **Save current** to keep the edited version as a named variation. Next, learn how to change [population projections and comparisons](/analysis/projections-and-comparisons).