The C: drive isn’t meant to store everything — and yet, Windows saves everything there by default. That’s what causes it to fill up faster than it should, and moving things to another drive after the fact isn’t always straightforward. I ran into this exact issue on my PC, and the fix was simple too. I simply had to tell Windows to store things in other drives.
Windows dumps everything in C: drive by default, and that’s a problem
It’s not meant for that
The reason my C: drive kept filling up wasn’t hard to figure out. Windows puts almost everything new there by default. This includes apps, downloads, temporary files, Windows updates, documents, and even files created by third-party apps. So it’s not hard to see why the C: drive gets full so quickly.
Of course, this isn’t necessarily a problem if your PC has plenty of storage or if you haven’t bothered to partition the drive. But if, like me, you’ve got a small C: drive and a much larger second drive, it can throw everything out of balance. Your PC might have hundreds of gigabytes sitting unused on another drive while Windows keeps complaining that the C: drive is running out of storage.
C: drive getting full is a problem because it leaves Windows with little room for temporary files, caches, updates, and background tasks. The most obvious downside here is the performance hit. Windows has to constantly delete existing temporary files and cache to make room for new ones. That extra processing slows things down. Apps can take longer to load, updates might refuse to install, files may not save correctly, and in extreme cases, Windows might even crash. So yes, C: drive getting full is not something you can ignore.
I stopped Windows from saving everything to the C: drive
The permanent fix
For weeks, I was constantly moving data off the C: drive every time it turned red. It worked, but it wasn’t the solution. The underlying problem was Windows saving my apps and downloads to the C: drive, so that’s what I had to change.
Windows lets you do this from the Settings menu itself. Head to Settings > System > Storage > Advanced storage settings > Where new content is saved. Here, use the drop-down menus under each section to specify where you want to save new apps, documents, music, photos, videos, and more.
This doesn’t affect browser downloads, though. They still go to the C: drive by default, and to change that, you need to head to your browser settings. There, go to the Downloads section and look for the Location option. This will tell you where Windows is currently saving downloads. Click the Change button to point it to somewhere else.
Both these changes apply to the new downloads, so your existing apps and files aren’t affected. You can move those to another drive too, but it’s not exactly straightforward. For games, you need to rely on your game launcher, like Steam, Epic Games, EA, or Rockstar Games to move files around without breaking anything.
For apps downloaded from the Microsoft Store, head to Settings > Apps > Installed apps, click the three-dot icon next to the app, and choose Move. You can then choose the drive where you want to move the app. Apps and programs you’ve installed outside of the Microsoft Store aren’t always easy to move, so your best option is to usually uninstall them and reinstall them on a new drive.
You don’t have to stop here
Free up C: drive manually
Telling Windows to save everything to the D: drive solves the problem of the C: drive filling up. But if you’re still short on storage, you can try other things to free it up. The most obvious is Disk Cleanup. This takes care of all the temporary files, old update data, thumbnail cache, and other useless things Windows accumulates over time. While using it, make sure to click Clean up system files for a more thorough pass.
Hibernation is another feature that can eat a lot of space on your C: drive. When enabled, Windows saves a snapshot of your entire RAM in a file named hiberfil.sys on the C: drive. This can be anywhere from 60% to 75% of your PC’s RAM size, and the annoying part is that Windows keeps this space occupied permanently, regardless of whether you’re using hibernation or not. The only reliable way to get rid of it is to disable hibernation. For that, open the Command Prompt with admin privileges and type powercfg /h off, and hit Enter.
The paging file is another storage hog, because Windows manages it automatically. You can change the paging file size to manual so Windows can’t use more than the set storage for virtual RAM.
Doing these things should free up the C: drive and give you enough runway for a few months. Of course, if it’s substantially small, extending or upgrading it is still your best bet.
