The Fernwasser Elbaue-Ostharz (FEO) is a long-distance water network of 800 kilometers in length covering several different regions of Germany. The network is comprised of large pipelines up to DN 1200 which transport around 220 million litres of drinking water to the central German region every day. One of the three waterworks in the network, the Wienrode, is connected to the Rappbode dam of the Talsperrenbetrieb Sachsen-Anhalt AöR. Once the transported raw water has been treated it provides about 40 % of the drinking water requirement of the Saxony-Anhalt region. Part of the infrastructure of the Wienrode waterworks, operated by FEO, is a bypass system connecting two individual 800 mm supply pipes to the waterworks. Two Katronic KATflow 150 clamp-on ultrasonic flowmeters are installed on these bypass pipes and are used to control the flow at these critical points.