This Technical Report applies to industrial and district heating supply by means of high-temperature water heating facilities (flow temperature > 100 °C). This also applies to high-temperature water heating facilities (flow temperature ≤ 100 °C) that are directly connected to district heating networks. In this Technical Report, the aforementioned supply variants will, in the following, be referred to as “district heating facilities”. This document applies without limitations to new facilities. For existing district heating facilities, the application of this Technical Report is recommended in order to prevent faults due to the chemical composition of the circulation water that would affect the facilities' safe operability and availability. NOTE Informative notes in the form of guidance and recommendations are identified correspondingly and set in italics for better differentiation.