Wastewater

Efficient wastewater treatment protects the Baltic Sea.

The residents and companies of the Helsinki Metropolitan Area produce about 130 million cubic metres of wastewater yearly. The sewer network directs the wastewater to the treatment plant for processing before it is returned to the water system. The treated wastewater is directed back to the water system. HSY treats household and industrial wastewater in the Helsinki Metropolitan Area with its two wastewater treatment plants in Viikinmäki, Helsinki and Blominmäki, Espoo. 

Households can reduce the wastewater load and prevent sewer blockages by following the sewer etiquette. This means that nothing that does not belong there is put down the drain.   

Discharge of industrial wastewater and other non-domestic wastewater to the sewer system always requires a permit. The terms of industrial wastewater discharge are defined in the industrial wastewater agreement.