How the fuck did Windows 10 fill another 30 GB of hard drive without my help?

my  win-10  [c=#800000][b]c:drive[/b][/c]  uses  about  45gb … i  keep  personal  files  on  separate  drive … consider  this  as  just  a  point  of  reference.

did  you  turn  win-10  updates  off?  how  long  ago  did  you  turn  win-10  updates  off?  which  exact  version  of  win-10  do  you  have?  not  which  [i]'edition'[/i] … which  version?

go  to  [c=#800000]pc-settings/system/about[/c] … scroll  half-way  down … it  will  tell  you:
     ◦ edition
     ◦ version
     ◦ version-install  date
     ◦ os-build
tell  me  all  the  above.

afterward … go  to  [c=#800000]control-panel/program-features/installed-updates[/c] … this  would  inform  you  if  updates  have  recently  been  applied.

   [c=#800000][b]windows.old[/b][/c]
let's  check  a  few  other  things … if  you  had  a  previous  version  of  win-os [i](8.1/8.0/7)[/i] … upgrading  to  win-10  creates  a  separate  directory … in  case  you  wish  to  return  to  the  previous  os.  the  name  of  this  directory  is  [c=#800000][i]"windows.old"[/i][/c].  this  directory  takes  up  lots  of  hard-drive  space.  so … this  may  be  one  of  the  storage  hogs.

after  carefully  considering  the  ramifications … if  you  still  wish  to  delete  that  windows.old  folder … go  to  disk-cleanup [i](admin priv)[/i] … click  [c=#800000]"system-files"[/c] … check-mark  [c=#800000]"prev-wind-inst"[/c] … and  once  you  click  [c=#800000]"ok"[/c]  the  file(s)  will  be  removed.

   [c=#800000][b]system-restore-points[/b][/c]
another  storage  hog  is  system-restore-points … you  should  retain  only  one  restore-point … previous  ones  can  be  removed.  these  take  up  lots  of  space  on  disk-drive.

[sep]

ref:
https://www.cnet.com/how-to/how-to-delete-the-windows-old-folder-from-windows-10/
https://betanews.com/2018/05/02/free-up-30gb-windows-10-april-2018-update/
https://www.zdnet.com/article/faq-how-to-manage-windows-10-updates/
https://www.computerworld.com/article/3199077/microsoft-windows/windows-10-a-guide-to-the-updates.html

[sep]

   [b][c=#800000]eula[/c][/b]
[i][c=#800000]i  assume  you  have  a  basic  understanding  of  how  computers  operate.  only  do  the  above  procedures  if  you  feel  comfortable  doing  so.  i  accept  no  responsibility  for  any  of  your  actions  or  decisions.[/c][/i]

@muffinman I have version 10.0.17134.48. I disabled automatic updates in Group Policy editor > Administrative Templates > Windows Components > Windows Update. It was pretty much the first thing I did after the OS was installed a few weeks ago. It wasn't upgraded from an older version of Windows. I have no restore points.

I've just found out the extra disk space isn't accounted for by the files in c:. Everything in there, including hidden things, totals to twenty-something GB. But when I right-click the drive in Explorer and click Properties, it says fifty-something GB is used.

this  past  tuesday [i](patch-tuesday)[/i]  my  win-10  climbed  from  17134.48  to  17134.112 … so  the  fact  you  disabled  updates  might  account  for  the  missing  112  update.

you  might  drop  by  a  computer-forum  and  feel  around … they  probably  can  offer  a  more  knowledgeable  opinion.
      www.bleepingcomputer.com/forums
      www.tenforums.com
      www.windowsforum.com

keep  the  spirit.

@waleskinder  and  then  there's  some  people  who  scream … no  matter  which  way  the  wind  blows.  <grin>

@Elessar Ha. I'm reading the Debian Installation Manual right now.