The Lake Maridalsvannet in Oslo seen from above
The City of Oslo’s drinking water comes from the nearby lakes of Maridalsvannet (photo) and Elvåga. From here, the City of Oslo uses around 100 million cubic metres of water for the city’s drinking water supply. Photo by: Wilhelm Joys Andersen
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Oslo water supply goes online to reduce high water loss

A new state-of-the-art online model of Oslo’s water supply will help reduce a high level of leakage and resolve a serious water challenge, which is threatening the Norwegian capital’s future supply of drinking water.

01. Nov 2018

In Oslo, 35 percent of the clean drinking water is lost on the way from waterworks to tap. The large volumes of drinking water seep out from leaks in the pipe network, and until now, focus on water losses in Norway has been limited.

But now the municipality of Oslo, which is responsible for the water supply in the Norwegian capital, has made an ambitious plan to reduce water losses and secure the future supply of clean drinking water to Oslo.

“We’re in need of a fact-based tool for decision-making, which can contribute to locating and eliminating weaknesses in our system. In order to act pro-actively and constantly optimise operations, we must have an overview of conditions in the pipe network and be able to analyse the consequences of different measures before we put them into action. Digitisation and knowledge will be the key to this essential optimisation,” says Chetan Hathi, who is a project manager with the City of Oslo’s department for Water and Sewerage Works.

Real-time overview of more than 1,550 kilometres of water pipes

Until 2022 the City of Oslo will execute a five-stage plan to reduce leakage. The plan includes introducing a standardised method to calculate water losses, to divide the pipe network into smaller areas, to control and optimise pressure in the pipe network and to strengthen analysis and reporting of key performance indicators.

The goal is to bring the leakage level in Oslo down to 20 percent by 2030. Furthermore, a key component in this five-stage plan is to establish an advanced online model of the entire supply network, which comprises 1,550 kilometres of water pipes. It will provide the supply company with a real-time overview of the water’s flow through the drinking water system and the pressure level in the pipes.

This will allow the City of Oslo to identify leaks early on by looking at water volumes, flow directions and variations in water pressure. At the same time, the model will also make it possible to monitor key performance indicators and thus improve the knowledge required to reach the target of reducing water losses.

Water challenge

Oslo is a city in growth. At present, approximately 700,000 citizens must be provided with clean drinking water. However, in the future the city expects to supply water to as many as 900,000 inhabitants.

The City of Oslo’s drinking water comes from the nearby lakes of Maridalsvannet and Elvåga. From here, the municipality uses around 100 million cubic metres of water for the city’s drinking water supply. But for a number of years the city has wanted a new source of drinking water. In part, fluctuating drinking water quality can threaten the supply security, and if two or more years of drought occur in a row, there may be a lack of drinking water from the two lakes. On top of that is an increase in demand for water, because of the growth in population.

This means that there is a need to rethink the strategy in order to secure the capital’s future drinking water supply. However, new water sources to supply up towards a million people cannot be solved with a quick fix. The answer may therefore be to reduce the amount of drinking water that is lost due to leakage. This will save approximately 35 million cubic metres of water every year – or slightly more than a third of the city’s current water requirements.

State-of-the-art technology

Controlling water losses in Oslo is probably not enough to ensure the future water supply. However, it may serve as a temporary solution, until the City of Oslo has secured a new source to supply the city. These are the words of Gitte Marlene Jansen, who is a project manager with NIRAS.

Along with Danish and Norwegian specialists from NIRAS, she is currently working closely with the City of Oslo to establish new, advanced technology that will help optimise the supply and determine where the 57-year-old drinking water system is leaking.

As a consultant to the municipality of Oslo, NIRAS is establishing the online model – the Aquis system– which will cover all of the supply network’s water pipes. In addition to Aquis, the management information system HOMIS, which is developed by NIRAS, will be implemented. When the basic system is configured, the team of consultants will train the Norwegian technicians, so they themselves will be able to operate the system.

“This is not just a project delivery and then on to the next task. This is a long-term partnership, where we will help the City of Oslo during a period of at least four years to take a step closer to achieving a sustainable and future-proof water supply. The client has ambitious targets and has chosen to invest both time, money and resources – and we have the necessary tools and expertise. I find it very exciting,” says project manager Gitte Marlene Jansen.


Oslo is a city in growth. In the future the city expects to supply water to as many as 900,000 inhabitants.