- operation of sewer systems or sewer treatment facilities (pipelines, sewers, channels, canals, regulating lakes etc.), pumping stations for rainwater and wastewater drainage, waste water treatment works and other auxiliary works for the purpose of collecting and transporting, drainage of rain water, waste water, anti-flood and waste water treatment; - collecting and transporting of human or industrial wastewater from one or several users, as well as rain water by means of sewerage networks, collectors, tanks and other means of transport (sewage vehicles etc.); - repair and maintenance of sewer system.