The article discusses the issues of improving the efficiency of heat supply organizations in the turbulent external environment. Fight for survival in difficult economic conditions compounded by a high degree of deterioration of the majority of heat networks, which are the most fragile element of the heating systems. Regular and timely assessment of the reliability of heating networks, as a necessary condition for the long-term existence and further development of heat supply organizations, allows us to solve a number of issues: to draw a conclusion about the current state of heating networks, prevent possible failures or breakdown of heating equipment, ensure their further operation with a minimum of restoration costs. Example of calculating the reliability of thermal networks, presented in a paper made using the recommendations on the analysis of indicators for assessing the reliability of heat supply systems, set out in the Order of the Ministry of Regional Development of the Russian Federation from July 26, 2013 number 310.