Water networks

​Water supply ne​​twork

The total length of the water supply networks in the Helsinki Metropolitan Area is 3,000 kilometres. Around 300 kilometres of this is taken up by the main supply network, which conducts water to water towers and large consumption centres. The distribution network branches from the main network, connecting to the supply pipes of plots.

Sewer​​ network

The total length of the sewer network in the Helsinki Metropolitan Area is around 4,900 kilometres, of which 2,700 kilometres are wastewater and combined water sewers and 2,200 kilometres stormwater sewers. There are around 80 kilometres of sewer tunnels mined into a rock.

The Helsinki Metropolitan Area uses two sewer systems. A separate sewer system is used outside the Helsinki inner city and in Espoo, Vantaa and Kauniainen. In areas using a separate sewer system, only the wastewater is conducted into the water treatment plant through the sewers, whereas stormwaters are conducted to the closest body of water.

The inner city of Helsinki mostly uses combined sewers, which conduct both wastewater and stormwater in the same sewer to the Viikinmäki water treatment plant. The combined sewers take up top 6 percent of the total length of sewers.

Wastewater pu​mping stations

Wastewater sewers are aimed to be planned so that the wastewater would flow to the water treatment plant aided by gravity. Due to the height differences of terrain, this is not always possible, which is why wastewater pumping stations are needed.

 The Helsinki Metropolitan Area has over 500 wastewater pumping stations. Most of these stations are located underground and only around thirty of them are situated above ground. The largest stations are located in Suutarila and Pukinmäki.

The stations are situated near residential centres and in some cases they may cause an odour problem for their close surroundings. Some of the largest stations have been equipped with odour removal systems, which are based on a chemical filtering mass.  The exhaust air of smaller stations is, in some cases, conducted through odour-removing activated carbon cartridges. HSY has one biological odour control tool in use in Espoo.

You can report any odour problems caused by the wastewater pumping stations through theHSY feedback form. Feedback from the residents has an important role when we assess the construction and functionality of odour control systems.