Municipal wastewater - KOSTRA, 2009

Unless renewal increases to a higher level, this will unavoidably lead to aging wastewater pipelines throughout the municipalities. Even without new installations, it will - given the current renewal rate - take more than 200 years to renew the whole pipeline system.

Most renewals in Oslo and Hordaland

Renewals tend to vary from one year to another. The key figure “Percentage of total sewage pipeline system renewed, 3-year average” will downsize these cyclical variations. The municipalities in the counties of Oslo (1.16. per cent), Hordaland (1.13 per cent) and Vestfold (0.70 per cent) renew the most, while Vest-Agder (0.30 per cent), Østfold (0.26 per cent) and Aust-Agder (0.14) renew the least.

The renewal of sewage pipelines is of critical importance to prevent damage to buildings and pollution through leakages. Leaking pipelines can also contribute to higher treatment costs as surface water and groundwater can enter the pipelines.

Akershus and Rogaland have the longest sewage system

Estimations for 2009 show that there are around 35 200 kilometres of municipal sewage pipelines in the whole country (not including separate storm water pipelines), which is equal to approximately 88 per cent of the circumference of the earth at the equator. The sewage pipelines can be divided into 7 600 kilometres of combined sewage and storm water and 27 600 kilometres with a separate sewage system. The municipalities in the counties of Akershus and Rogaland hold the longest sewage system, while counties in Nordland have the largest share of combined sewer systems.

In addition to the 35 200 kilometres of sewage systems, there is also an additional 13 800 kilometres¹ of separate storm water pipelines. Hence, there are around 49 000 kilometres¹ of municipal wastewater pipeline systems in Norway.

Half the sewerage system less than 30 years old

A total of 4.5 per cent of the municipal sewage pipelines were installed before 1940, while 50.9 per cent were installed in 1980 or later. In addition, the installation date of 10.4 per cent of the pipelines is unknown, but it is likely that they are old. The renewal rate for this category is relatively high at 1.8 per cent in 2009. By comparison, there was a 0.39 per cent renewal rate for sewage pipelines installed before 1940 and a renewal rate of 0.21 per cent for pipelines installed in 1980 or later.

One pumping station every four kilometres

Pumping stations are sometimes used to direct wastewater against gravity (uphill etc). For 2009 it has been estimated that there are around 8 700 municipally-owned pumping stations in Norway; an average density of 0.25 pumping stations per kilometre.

Variation in standard of sewerage pipeline systems

According to the 2009 figures, there were 90 sewage overflows per thousand kilometre of municipal pipeline system in the country. This constitutes a 7 per cent decrease compared to 2008.

The figures are not only related to the age of the pipeline systems, but there is a tendency that older pipelines give rise to more sewage overflows. In municipalities where the average age was below 25 years, the figure was 56 sewage overflows per thousand kilometre of pipelines, while this figure was 94 in municipalities with pipelines older than 50 years.

84 per cent of inhabitants connected to wastewater facilities of 50 pe or more

In 2009, it was calculated that there are around 84 per cent of inhabitants connected to municipal wastewater facilities of 50 person equivalents (pe) or more. Private solutions are most common among small wastewater facilities (less than 50 pe). The 1.0 per cent deviation between reported data on inhabitants connected and official population statistics - shown in the table - reflects the uncertainty in the reported data for inhabitants connected.