District heating networks are some rather expensive infrastructures and should last as long as possible. Managers of DH networks focus on how best to maintain and secure their networks. When the pipes are in the ground, the only factor one can control is nearly the operation and maintenance cost – it is tough to see the pipes again, or maybe not that hard if done from above. For this interview, Morten Jordt Duedahl has invited two specialists in surveying DH networks to discuss how it is done. Bo Jensen Møller, Head of Operation at the Copenhagen DH company HOFOR and Sune Nielsen, tech- and drone wizard, inventor, and COO of the Danish company Drone Systems.