The technical regulations for drinking water installations are currently being revised. To help users understand this new complex concept derived from European and national regulations, the ZVSHK is publishing comments on the individual standard parts. DIN EN 806-4 contains recommendations and requirements for the installation of drinking water systems within buildings and for the installation of pipelines outside buildings but within property boundaries. This document applies to new installations, renovations, and repairs. The fourth part of the DIN EN 806 standards series is very practice-oriented and is therefore of particular importance to the installation trade.