Wastewater is the water, the quality of which was deteriorated by human activities.
The wastewater is divided into the municipal wastewater and industrial wastewater. Before the water is returned to the nature (streams, rivers), it must be treated.
SmVaK Ostrava operates the sewage system and wastewater treatment facilities in Frýdek-Místek, Karviná, Nový Jičín, Opava and Bruntál. In the system, there are 1,740 km sewage pipelines and 65 wastewater treatment plants. More than a half million people are connected to the SmVaK Ostrava’s sewage system.
SmVaK Ostrava operates its own facilities as well as many wastewater treatment plants which are owned by the municipalities.  The operation contracts have different scopes – from technical support to complete operation of the sewage system and wastewater treatment plant.