is it normal for the system files to be over 70 GB on Mac air?

Solution 1:

This is expected in many cases, since everything is initially classified as other and only things that are clearly in your home folder and belong to a more narrow category come out of “system”.

I would check that you only have one user account on the Mac and then set up Time Machine. If you set the Mac to not sleep and let a day of backups happen, check back and see if the system usage has shrunk.

Normally the system can self clean, but having the backup lets you erase and get a clean start if there’s not a quick way to identify why the storage isn’t freeing or what is taking up the space.

Once you know the first backup is running, click manage to dive deeper and look at what you can optimize or free up in each category.

• https://support.apple.com/en-us/HT206996