The guideline supports the planning, operation and maintenance of service water installations. It deals in particular with the use of grey water, rainwater, surface water and process water. The following applications are considered in particular: watering of greenery, cleaning, toilet flushing, commercial use, cooling water, firefighting installations. The guideline defines the requirements to be met by interfaces or transfer stations between the potable-water installation and the service water installation. The guideline aims to describe the planning of service-water installations in combination with other building services while ensuring health and environmental protection.