Stormwater sewerage area

The stormwater sewerage area includes the areas with HSY’s stormwater sewers. According to the Water Services Act, properties located in a stormwater sewerage area must be connected to a water utility’s stormwater sewer network.

We have reviewed the stormwater sewerage area and the cities of the Helsinki metropolitan area have confirmed it. The revised area entered into force at the beginning of 2019. In the review, we determined which properties are located in the stormwater sewerage area. There are approximately 63,000 properties in the revised stormwater sewerage area. Some 8,000 properties have been added to the area and approximately 2,500 properties have been removed from it. No changes have taken place for approximately 50,000 properties.

We updated the billing criteria for properties added to the stormwater sewerage area in connection with our invoicing reform in the spring of 2020. For example, the basic rate for stormwater of a detached house with a floor area of 175 m2 is approximately EUR 26 per year. 

Stormwater sewerage areas on a map

You can check the map to see if your property is in the stormwater sewerage area. The map shows the following areas:

Blue = Stormwater sewerage area
Grey = Combined sewerage area
Brown = Areas to which stormwater sewerage will be extended

Map of HSY’s stormwater sewerage area


The embedded map does not work on mobile devices. On a mobile device, the map can be viewed in HSY’s map service.

You can move around the map by zooming in and out and by dragging the map. You can check the location of your property in the stormwater sewerage area by using the property’s address. Open the link to HSY’s map service, enter the address of your property in the Search field in the upper left corner, and press Enter. The map will automatically move to the location of your property.

The basic rate for stormwater must be paid if:

  • your property is located in one of these three areas; or
  • your property has a stormwater connection and your property is located outside the stormwater sewerage area.