Municipal wastewater - KOSTRA, 2011

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

Highest renewal rates in Oslo, Hordaland and Vestfold

Renewals tend to vary from one year to another. The key figure “Percentage of total sewage pipeline system renewed, 3-year average” will even out these cyclical variations.

For the 3-year period 2009-2011, the municipalities in the counties of Oslo (1.46 per cent), Hordaland (0.59 per cent) and Vestfold (0.58 per cent) renewed the most, while Nord-Trøndelag (0.21 per cent) and Aust-Agder (0.26 per cent) renewed the least.

In 2011, 38 per cent out of 401 reporting municipalities (430 in total) reported that at least part of the sewage pipeline system has been renewed, 10 per cent specified no renewal and 52 per cent were non-respondents. Corresponding figures on installation of new pipelines were 51, 16 and 33 respectively.

The renewal of sewage pipelines is of critical importance to preventing damage to buildings and pollution through leakages. Leaking sewage 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 2011 show that there were around 35 700 kilometres of municipal sewage pipelines in the whole country (not including separate storm water pipelines), which is equal to approximately 89 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 28 100 kilometres of a separate sewage system. The municipalities in the counties of Akershus and Rogaland hold the longest sewage system, while counties in Oslo and Nordland have the largest share of combined sewer systems.

In addition to the 35 700 kilometres of sewage systems, there is also an additional 15 300 kilometres of separate storm water pipelines. Hence, around 51 000 kilometres of municipal wastewater pipelines exist in Norway in total.

30 years old pipeline system

The exact age of municipal wastewater pipelines will normally differ across regions - also within a single municipality - but for the country as a whole, it has been estimated at around 30 years old (37 years when adjusted for pipelines laid down in an unknown period ). A total of 2.8 per cent of the municipal wastewater pipelines were installed before 1940, while 44 per cent were installed in 1980 or later.

In 2011, the renewal rates were highest for the oldest part of the sewage system, with 0.78 per cent renewal for the pipelines laid before 1940. By comparison, there was a 0.10 per cent renewal of sewage pipelines installed in 2000 or later.

One pumping station every four kilometres

Pumping stations are sometimes used to direct wastewater against gravity (uphill etc). For 2011, it has been estimated that there are around 9 000 municipal-owned pumping stations in Norway; an average density of 0.25 pumping stations per kilometre.

Variation in standard of sewerage pipeline systems

An estimated 2 400 sewage overflows have occurred throughout the country in 2011. This corresponds to 67 sewage overflows per thousand kilometre of municipal pipeline system - an 11 per cent decrease compared to 2010.

Furthermore, the municipalities have accepted liability to around 400 closed cases of basement flooding in 2011.

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

For 2011, it has been estimated that slightly less than 85 per cent of inhabitants are connected to municipal wastewater facilities of 50 person equivalents (pe) or more. Private solutions are most common among wastewater facilities less than 50 pe. The -1.9 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.