Skip to main content
SLU:s publikationsdatabas (SLUpub)


Förebyggande av rotinträngningar i VA-ledningar - utveckling av beslutsstöd

Östberg, Johan; Stål, Örjan; Martinsson, Max; Fransson, Ann-Mari


In 2007 data regarding sewage pipes and CCTV-inspections of the sewage pipe interior, a total of 1 113 sewage pipes with 3 417 root intrusions, was collected from the three cities; Malmö, Skövde and Katrineholm. In 2008 additional data was collected consisting of an inventory of 4 590 trees in Malmö Skövde and Katrineholm, and CCTV inspections in another city, Växjö. Another 74 778 trees were inventoried and 23 312 trees registered from the participating cities’ databases. These trees were geographically distributed throughout the cities. Overall this constitutes a database of 102 680 trees. By using the collected data, analysis showed that PVC-pipes have less root intrusions penetrating through the joints than pipes made of other materials. However, PVC-pipes have more root intrusions per meter pipe. This is probably due to roots entering the pipes through service connections and at the transition between PVC and other materials. The reason why PVC has less root intrusions that have penetrated through the joints compared to concrete pipes can also be affected by the joint frequency which is significantly lower in the PVC pipes. By this comparison it is not concluded that PVC is better or worse to resist root intrusions than concrete. We can see indications that a large share of the root intrusions might be avoided if fewer damages were present on the pipes and if the connections were made in a more root-resistant manner. These indications demonstrate that root intrusions even in the future will be a serious operational problem, despite the use of pipes with high sealing ability of the joints or the jointless pipes. The survey also showed that renovated pipes have problems with root intrusions a relatively short time after the renovation from root intrusions. Root intrusions into renovated pipes may have occurred at the manholes or at the service connections. To overcome the problem with root intrusions future research must be directed to enhance the sealing capacity along the whole pipeline, rather than on individual sealings. The investigation has shown that the minimum distance of three meters that was previously recommended in order to reduce the risk of root intrusion is insufficient. We can see a high number of trees at a distance between 3 to 7 meters from the root intrusions, and we suggest that the distance be increased to 7 meters. This will create challenges for the landscapers, but it is of great importance if to reduce the number root intrusions in the future. The species that have been regarded as more or less likely to give rise to root intrusions has previously been listed. This project provides a new such list. In this list both willow, poplar/aspen, roses and thuja occurs. It is thereby clear that even shrubs can cause root intrusions. The species that occur with a higher frequency close to root intrusions are also interestingly not only willow, poplar/aspen. In addition it seems that the species that are frequent surrounding root intrusions are not the same in the cities investigated. In light of these results, previous recommendations must be taken with some caution


Avloppsledningar; dagvattenledningar; trädrötter; rotinträngningar

Publicerad i

Svenskt vatten utveckling rapport
2010, nummer: 2010-04
Utgivare: Svenskt Vatten AB