The article considers specific features of the environmental and technological transformation of the Russian economy aimed at reducing negative environmental impacts and enhancing the resource efficiency of production. We analyze the results achieved by water-supply and wastewater treatment enterprises. It is noteworthy that the Russian Federation is the only country where such enterprises are classified as belonging to category I of negative environmental impact, which obliges them to implement Best Available Techniques (BATs) and obtain Integrated Environmental Permits. The sector has joined the environmental and technological transformation on its own initiative and a unique BAT Reference Document has been developed for water supply and wastewater treatment enterprises. Technological indicators (or BAT-associated Emission Limits) (requirements for the composition of wastewater upon treatment) were established. They vary depending on the size of the treatment facilities and the category of the receiving water bodies. Enterprises of the sector are leaders in the development and implementation of environmental and technological modernization programs: 75 % of the Integrated Environmental Permits granted to enterprises involve the implementation of such programs. The article analyzes the experience of St. Petersburg Vodokanal (water supply and wastewater treatment enterprise), whose sewage treatment facilities are undergoing gradual reconstruction and modernization and ensure proper treatment of 99.8 % of the municipal wastewater. Saint Petersburg Vodokanal and Petrozavodsk Vodokanal became the first facilities with negative environmental impact to be excluded from the lists of regional environmental “hot spots” based on decisions of international organizations and compliance with BAT-associated requirements. We conclude that the experience of St. Petersburg Vodokanal in implementing a continuous self-monitoring system for treated wastewater should be replicated at other facilities, with adjustments for their size. Such a solution will enable fulfillment of the environmental legislation requirements established for the transition to environmental and technological regulation of key economic sectors.