E6 Clean Water Tunnel

New Waters for Oslo

E6 Clean Water Tunnel is part of the new water supply project for Oslo that will ensure 100% supply for the current drinking water transmission system, with about 18 km of multiple tunnelling routes dug into the rock.


Ghella, in a joint venture with AF Gruppen, has been awarded by the Municipality of Oslo the E6 Clean Water Project for the construction of a new water distribution network, between Huseby, Oset and Stubberud.

The project is part of the creation of a water reserve for the population of Oslo and involves the construction of a new drinking water supply system consisting mainly of transmission lines, pumping stations and clean water basins, as well as connections to existing main pipelines and to the water treatment plant in Oset.

The New Water Supply Oslo includes: the Holsfjorden water supply tunnel, the underground water treatment plant in Huseby and the pre-treated water transfer tunnel from Huseby to Stubberud. It will connect to the water treatment plant already in operation, strengthening the link between east and west Oslo.

In this way it should be ensured always and, in any case, a correct supply of drinking water.


A Few Numbers

Lake Maridalsvannet currently provides drinking water to 90% of Oslo’s population. A breakdown in the water supply system of this network could therefore have serious consequences for the entire city, which is why a large-scale reserve water supply will be established thanks to this new distribution system. The structures will be built underground, with around 18km of multiple tunnelling drives. The 11 km tunnel from Stubberud to Huseby will be drilled with Tunnel Boring Machine (TBM) while the remaining 7 km with traditional method (drill and blast). The new tunnel will be built with more connecting points that will be connected to the existing water supply along the route.

Ghella NUF Statement of transparency act