Fix: C Drive Filling Up by itself on Windows

If your C drive is filling up without a reason, it can be due to a malware attack, file system corruption etc. The C drive is usually taken as the System partition on a computer system. System volume is the partition where your Windows is installed and where all the third-party programs intend to install by default. Having some free space in your C drive is essential as it is often needed during a Windows update or upgrade.

However, in some cases, the C drive fills up by itself which can be really hideous. Some users have reported that when they check the drive’s properties, it shows that the drive is full. However, when they open the drive and select all the folders, the size is but only a portion. Therefore, we are here to help you out of this issue.

What causes the C Drive to Fill Up by Itself on Windows 10?

Since the C drive is mostly the system volume, therefore, the disappearing of free space can be due to the following factors —

  • Malware attack. If your system is affected or under control of malware, it can cause the disappearance of free space on your system volume.
  • Corrupted system files. The damage or corruption of your system files can also donate to the vanishing free space.
  • System restore points. Sometimes, machines are configured to utilize more than the sufficient amount of space required for a system restore point which can cause the issue.

We have salvaged a few effective solutions that you can implement to solve your issue. Please make sure to go through them all if the issue persists.

Solution 1: Scan your System

Starting off with the most general cause, you should run a thorough system scan using Windows Defender or any other third-party antivirus in order to detect any malware that is present on your system. If you have turned off your Windows Defender without having a third-party antivirus on your system, certain malware can easily corrupt your system as it is wide open. Hence, make sure to always have Windows Defender on except when it’s interrupting a certain task that you are performing. To perform a full scan on your system using Windows Defender, do the following:

  1. Press Winkey + I to open Settings.
  2. Go to Update and Security.
  3. Switch to the ‘Windows Security’ tab.
  4. Click on ‘Virus and threat protection’.
    Windows Defender Settings
  5. Hit Scan options and select the ‘Full Scan’ box.
    Windows Defender Full Scan
  6. Run the scan.

Solution 2: System Restore Points

Like we mentioned earlier, in some cases, system restore points are allocated more space than that is required which results in the issue. Hence, to fix this, you will have to decrease the amount of space allocated to system restore points. Here’s how:

  1. On your Desktop, right-click ‘This Computer’ and select Properties.
  2. Click on ‘System Protection’.
  3. Hit the Configure button.
    System Properties
  4. In the new window, move the slider to the left to lower the space allocated to System restore points.
    Changing System Restore Settings
  5. You are also allowed to disable Windows Restore but we would advise against that. Just decrease the amount of space allocated to the restore points.

Solution 3: Running Disk Cleanup

Disk Cleanup is a utility that scans your hard drive and frees up space for you to utilize in the future. If you haven’t performed a Disk Cleanup in a long time, the temporary files stored on your C drive can be occupying lots of space. Therefore, to free up some space, you’ll have to delete the temporary files. Here’s how:

  1. Go to Start Menu, type in Disk Cleanup and open it up.
  2. The C drive is selected by default so just click OK.
  3. On the list, check the boxes for things like ‘Temporary files’, ‘Previous Windows Installations’ etc. and then click OK.
    Cleaning up Temporary Files
  4. Wait for it to complete.

Solution 4: The Hidden Files

There are many hidden files created when you install Windows or after installing third-party programs which you cannot view or access by default. In order to view them, you’ll have to turn on the ‘View Hidden Files’ option. Here’s how:

  1. Open Windows Explorer.
  2. Click on File on the top-left corner and select ‘Change folder and search options’.
  3. Switch to the View tab.
  4. Locate Hidden files and folders and check the ‘Show hidden files, folders, or drives’ option.
    Enabling Hidden Files
  5. Hit Apply and then click OK.

After you have done that, check your drive for any unneeded files that are consuming too much of the storage. However, make sure not to delete Windows system files as it will result in a system failure and you’ll have to reinstall Windows.

Solution 5: Checking for System Files Corruption

Sometimes, if your system files are corrupted or damaged, you won’t be able to utilize much of your C drive storage. System files corruption is critical and should not be taken on a lighter note. Nonetheless, there are Windows utilities that will scan your system for any corrupted files and repair them. In this case, we will be utilizing the CHKDSK utility which searches for any bad sectors on your drive and repairs them.

For a more detailed guide, please refer to this article published on our side that will show you how to use CHKDSK.


Kevin Arrows

Kevin Arrows is a highly experienced and knowledgeable technology specialist with over a decade of industry experience. He holds a Microsoft Certified Technology Specialist (MCTS) certification and has a deep passion for staying up-to-date on the latest tech developments. Kevin has written extensively on a wide range of tech-related topics, showcasing his expertise and knowledge in areas such as software development, cybersecurity, and cloud computing. His contributions to the tech field have been widely recognized and respected by his peers, and he is highly regarded for his ability to explain complex technical concepts in a clear and concise manner.