- operation of sewer systems or sewer treatment facilities

- 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.)

- emptying and cleaning of cesspools and septic tanks, sinks and pits from sewage; servicing of chemical toilets

- treatment of wastewater (including human and industrial wastewater, water from swimming pools etc.) by means of physical, chemical and biological processes like dilution, screening, filtering, sedimentation etc.

- maintenance and cleaning of sewers and drains, including sewer rodding