Since its inception in 2015, Microsoft's storage requirements for Windows 10 have always been 16GB for 32-bit systems and 20GB for 64-bit operating systems. Next month, Windows will launch the May 2019 update, and one of the changes it brings is the change to the minimum storage requirement for OS.
According to Microsoft's official site, the new Windows 10 version 1903 storage requirement will be increased to 32GB for both 32-bit and 64-bit versions. For comparison, it has doubled the requirements for the previous version and 12GB more than the last.
The page does not explain Microsoft's decision to increase the required memory capacity. However, some Windows 10 users suggest that it has something to do with the new Reserved Space features for future updates.
Growth is unlikely to affect consumer systems. Considering the storage options available in most of the current HDDs and SSDs, as well as our increasing dependence on the cloud storage platform.
(Source: Microsoft using Hot Hardware)