The 30-Day Trash Limit
Since macOS Sierra, Apple has included an automated storage optimisation feature that automatically empties files from your Trash bin after they have been sitting there for 30 days. While this is an excellent way to prevent your hard drive from silently filling up with gigabytes of forgotten, deleted files, it can be disastrous for users who treat the Trash bin as a temporary holding area. If you frequently rely on digging through your Trash to recover files you deleted weeks ago, you need to turn this automation off to prevent permanent data loss.
How to Disable the Automatic Trash Deletion
You can instruct Finder to keep all deleted files in the Trash indefinitely, only removing them when you manually click “Empty Trash.”
1. Click on the desktop background to ensure the Finder menu is active at the top of your screen.
2. In the top menu bar, click on the word Finder.
3. Select Settings (or Preferences on older versions of macOS) from the drop-down menu.
4. A new window will appear. Click on the Advanced tab (the gear icon) at the top of the window.
5. Look for the checkbox labelled Remove items from the Trash after 30 days.
6. Untick this checkbox.
7. Close the Finder Settings window.
Managing Your Storage Manually
With this setting disabled, files will remain in your Trash bin forever until you explicitly right-click the Trash icon in your Dock and select “Empty Trash.” It is highly recommended that you keep an eye on your available storage space, as high-resolution videos and large applications moved to the Trash will continue to occupy physical space on your hard drive until the bin is permanently emptied.