Water conversation areas

15,38 % of the land areas of Germany were water conservation areas in 2018.

By the way, these zones are more than 18,000 different ones with an total area of almost 55,000 km².

Source: https://www.bmuv.de/themen/wasser-und-binnengewaesser/trinkwasser/trinkwasser-trinkwasserschutzgebiete