Today, Oslo Municipality’s potable water supply depends solely on Maridalsvannet and Oset water treatment facility, which supplies 90 % of Oslo with clean and safe potable water. If a major failure occurs in the current water supply system, Oslo will face severe consequences within a few hours. The overall goal of the projects ‘New water supply Oslo’ and ‘New water supply Oslo - Main network’ is to ensure the population in Oslo municipality a satisfactory supply of potable water, even in the event of failure of vital parts of the water supply system.