IKT Compare: Can Short Liners Repair House Connections?

man in manhole installing short liner

How do short liners perform? IKT figured it out in its latest IKT Compare project.

Short liners are often the first choice for repairing local damage in house connections. But, can they deal with seriously damaged pipes? The results of the new IKT-Compare project “Short Liner for House Connections” are now available.

IKT institute has found in its most recent IKT-Compare project that in principle short liners (also referred to as patch or point repairs) can make good quality repairs to house connection pipes, even when the pipe is severely damaged. Eight short liner systems were tested and achieved scores ranging from “VERY GOOD” to “SATISFACTORY”. The evaluation did find significant differences in performance between the systems that were examined.

Twinbond Liner was the best performer with a score of VERY GOOD (1.2). Second place went to epros DrainPacker (Trelleborg) also graded VERY GOOD (1.4). Bodenbender Point-Liner-System (1.7), Berolina Repair System (2.5), Cosmic TopHat system (2.5) and MC Konudur LM-Liner (2.5) each received a GOOD grade. Alocit short liner (2.7) and I.S.T. Spot Repair System (2.9) were graded SATISFACTORY.

The project has been undertaken in co-operation with twelve sewer network operators which wanted to understand the strengths and weaknesses of this widely used technology. It has been funded by the North Rhine-Westphalian Ministry of the Environment and the network operators.

Download table of results
Download product test report (German)

Tough testing of short liners

two men installing sewer pipes in testing facility

Deliberate defects: IKT has installed eight test sections with a total of 64 cases of damages in its large test pit.

A rehabilitation using a short liner should be able to restore the structural stability of a pipe, secure its hydraulic performance and seal a damaged area. For this reason, the IKT Compare team and the network operators involved placed particular emphasis during testing on the water tightness, operational reliability and structural stability of the rehabilitation. The particular focus was resilience external water pressure.

Test set-up damage scenarios

For this project IKT built eight identical 1:1 scale rigs, in its large-scale test pit (15m by 6m by 6m), into which suppliers installed their short liners. Each rig comprised a length of sewer to which were attached one house connection pipe on the same level as the sewer pipe and two house connection pipes from a higher level. The house connection pipes were prepared with defined areas of damage, including milled patterns of cracks, the removal of some or all of the joint seals and broken sections. A total of 64 damage patterns were produced – eight in each of the eight test rig setups.

members of steering committee looking at test set-up

Two up, one down: the test set-up.

These patterns of damage were arranged as follows:

  • Test Setup I (the lower house connection pipe, to which a 2m head of external groundwater was subsequently applied): cracks, a broken joint, a radially displaced joint and a joint displaced at an angle
  • Test Setup II (the two higher house connection pipes, to which a 1m head of groundwater pressure was subsequently applied): a defective change of pipe material, defective change of pipe diameter and material from cast iron DN 150 to PVC DN 125, a defective change of pipe diameter and material from clay pipe DN 150 to PVC DN 125, and a break in the joint of a 45 degree bend

Following installation of the eight different short liner systems into separate test rigs, an extensive testing programme began, starting with initial visual inspection and leak tests. This was followed by short-term and long-term external water pressure tests, high-pressure jetting at different pressures and using different types of nozzle, simulated backing-up of water, changing groundwater levels, and cleaning with rodding devices.

Frequent visual inspections and leak tests were undertaken as the programme progressed. Finally, when the test rigs were exhumed from the test-pit, the cross-section reduction was measured and the adhesive tensile strength and ring stiffness of the installed liners were assessed.

Grading of performance

construction site in front yard

In-situ tests: lab tests were validated through in-situ observation of the same systems being installed at actual construction sites.

In addition to physical tests, the QA/QC procedures were examined. The laboratory results were validated through in-situ observation of the same systems being installed at actual construction sites. The final scores in this IKT Compare test are based on these three evaluations. The range of grades applied is from VERY GOOD (score of 1.0) to INSUFFICIENT (score of 6.0).

Weighting of scores: Water Tightness counts for the most

To derive the final scores the results of the 1:1 scale testing system tests were given a 85% weighting and the results of the QA/QC evaluation 15%. For the 1:1 scale test score, the three test criteria were weighted as follows: “water tightness” (60 percent), “operational reliability” (20 percent) and “structural stability” (20 percent).

two men inspecting repaired sewer pipes

Ongoing observation. IKT testers regularly check the installed short liners for leaks.

The assessment of QA/QC comprised five criteria: the installation manual, the available training courses, the system’s DIBt (German Government’s approval body) approval, external production monitoring, and a comparison between the installations observed in the laboratory and in the field. The results for each criteria were given a 20% weighting in the final QA/QC score.

In addition to the test criteria used to derive the comparative scores of the systems, supplementary information was collected and presented that would be of interest to the end user. These include results from internal pressure tests undertaken after the rigs were excavated and the adhesive tensile strengths of the liner bonding to the host pipe. The preparatory measures undertaken by the installer, such as initial inspection, substrate preparation and cleaning, were documented. Also presented are: the number of on-site working days, the number of installation staff, the time required for preparatory work and installation, and the costs.

The Steering Committee – twelve cities

Members of the Steering Committee for the IKT Compare project “Short Liner for House Connections” are the following German cities: Billerbeck, Burscheid, Dortmund, Duisburg, Düsseldorf, Gelsenkirchen, Göttingen, Hagen, Herne, Rheda-Wiedenbrück, Schwerte, and Arnhem from the Netherlands.

What the systems can do

test rigs of house connections in testing facility

Repair objective: to seal damaged house connections.

In this IKT Compare project, the system suppliers demonstrated that serious damage to house connections can be reliably sealed using short liners, including breaks, cracks, misalignments and deflections. In particular, the Twinbond and Trelleborg systems proved to be the most reliable under permanent groundwater load, jetting, simulated backflow events and changing groundwater levels. For this they were deservedly awarded the score of 1.0 for water tightness.

Special Challenges

In principle, it was also shown to be possible to seal the changes in nominal diameter and pipe material in Test Setup II. However, four of the systems came up against their performance limits here, showing weak points, which led to infiltration. In one case, gushing water was visible immediately after installation. Therefore, changes in diameter and material require special attention during installation.

Results of Test Setup I

All eight short liners showed very good to satisfactory results for the four damage patterns in Test Setup I: cracks, broken joint, radially displaced joint and joint displaced at an angle. No infiltration was observed during the whole test period. However, about half of the systems showed visual abnormalities in the form of moisture and/or discoloration at some locations, but without the formation of droplets.

Structural stability assured

Adhesion test on short liner

Adhesion test

The structural stability testing of the short liners showed that they basically have reliable adhesive and load-bearing performance. For products with full-surface bonding of the liner to the host pipe, hardly any abnormalities were observed, i.e. no crack formation, no excessive deformation, no stability failure nor large-surface loosening of the adhesive bond. Five systems showed partial loosening of the adhesive bond at points of changing diameter or pipe material, albeit without any consequences.

The Cosmic system is not intended to bond over the full-surface, only at the start and end of the liner. However, the supplier was able to submit a static proof which confirmed the structural stability of the short liner observed in the test.

Operational activities

water from high-pressure-jetting splashing on test site

High-pressure jetting did not affect the short liners.

The test scenarios simulating sewer operation, such as high-pressure jetting, water backing-up in the pipe, and changing groundwater levels, had no significant effects on system performances.

Good QA/QC

There were no issues with quality assurance: seven out of the eight systems fulfil all the criteria for quality assurance and receive a grade of 1.0. The Cosmic system does not have a DIBt approval and so gets a grade of 2.0.


In conclusion the IKT Compare project “Short Liners for House Connections” has demonstrated that short liners can renovate even severely damaged sewer pipes. However, changes in diameter and material require special attention during installation as they might cause serious problems. It is important to select the right system for the task, to understand the limitations of individual systems, and apply the necessary QA/QC before, during, and after installation.

Download table of results
Download product test report (German)


IKT ‑ Institute for Underground Infrastructure, Germany
Serdar Ulutaş, MBA, Dipl.-Ing. (FH)
phone: +49 209 17806-32
email: ulutas@ikt.institute

IKT Compare: How good are products really?

three men preparing defined damages on the test rigs

Defined damages: preparing the test rigs

The objective of IKT Compare projects is to provide network operators with reliable, neutral, and independent information on the strengths and weaknesses of products and methods in sewer technology. IKT Compare projects are always undertaken in collaboration with network operators. Their representatives form a steering committee which takes all important decisions on how to test the products.

At the core are tests under realistic service life conditions such as traffic and ground loads, groundwater pressure and high-pressure jetting.
Each IKT Compare project is accompanied by a steering committee set up of network operators. The committee meets regularly and takes decisions on:

  • products to be tested
  • scope of the test programme
  • test criteria
  • test set-up
  • final grading and assessment of the test results

The actual testing and documentation of the results are carried out by IKT, as a neutral and independent institute. As a result, network operators are provided with independent, practice-related, and technically well-founded information on the strengths and weaknesses of products, their applications and limits.


Manhole Rehabilitation: Comparative testing of 13 different methods

manholes in IKT's large-scale test facility

On-site installation conditions simulated in IKT’s large-scale test facility

Can wastewater manholes be rehabilitated so that they remain permanently watertight? What are the benefits and the drawbacks of mortar coating, plastic coating and lining. What quality can be expected? This first comparative product test in this field gives you the answers!

“Now for the manholes” – this is a train of thought in the repair/rehabilitation departments of many wastewater network operators. There is, indeed, little point in rehabilitating wastewater pipes without paying attention to the numerous defective manholes. This is particularly true in water infiltration zones, since a really watertight sewer network can only be achieved provided the manholes are also rehabilitated.

Under test: thirteen manhole rehabilitation methods

Which of the many manhole rehabilitation methods should we choose? Which one will seal reliably and durably? Which is suitable in which situation, and which are not suitable? Thirteen commercially available methods have now been analysed in IKT‘s “Manhole Rehabilitation” Comparative Test. The results range from GOOD to ADEQUATE, with one method failing the test.

Comparative Test: Manhole Rehabilitation

Read the whole article with all test results (PDF, 10 pages)


Serdar Ulutaş
Dipl.-Ing. (FH), MBA

T: +49 209 17806-32
E: ulutas@ikt.de


Comparative assessment of innovative inspection procedures and equipment for site drainage systems

Sewer camera in use

Sewer camera in use

This research project involves the development of a test programme to comparatively test and evaluate the inspection procedures and equipment currently available for site drainage systems. Practical experience is to be gathered in pilot deployments in cooperation between the Meyer-Entsorgung disposal company and the City of Osnabrück. In addition, general recommendations for action to provide both the public and system operators with assistance prior to the actual inspection are to be drafted, based on experience from the City of Osnabrück. The project is receiving funding from the German Federal Environmental Foundation (DBU).


“Comparative assessment of innovative inspection procedures and equipment for site drainage systems and recommendations for action for preparation of the inspection (Phase I: Actual-condition survey, test programme and recommendations for action)”

Project management

IKT ‑ Institute for Underground Infrastructure gGmbH

Project participants

  • August Meyer Entsorgung – Technische Dienstleistungen GmbH & Co. KG (disposal organisation)
  • City of Osnabrück
  • Client

    German Federal Environmental Foundation (DBU)


    Christoph Bennerscheidt

    T: +49 (0) 209 17806-25
    E: bennerscheidt@ikt.de


IKT Comparative Test “Odour filters”

What will help against nasty smells from sewers?

What will help against nasty smells from sewers?

In the summer months, in particular, odour emissions from sewers cause odour nuisances and thus higher levels of complaints from residents. Sewer-system operators are in general obliged to find a remedy for such problems.

Odour filters installed in waste-water manholes are coming into increasing use. In addition, further products which release special active ingredients in the waste-water manhole shaft are also used. The aim of this Comparative Test was that of testing the odour filters for waste-water manholes available on the market together with the participating sewer-system operators for their fluid permeability, cleaning performance and easy usability, and to perform a comparative assessment of their quality. Products which release special active ingredients into the waste-air leaving such waste-water manholes for the suppression of such odours were also tested.


IKT Comparative Test “Odour filters”
with supplementary testing of other products for use in waste-water manhole shafts in case of odour nuisance


(German versions only)
Table of results
Test Report (127 pages)
Short Report (31 pages)


  • Kiel (capital of state of Schlewig-Holstein) – urban drainage utility
  • City of Ahaus
  • City of Frankfurt am Main
  • Hamm urban drainage utility (Lippeverband water authority)
  • Hannoversch Münden urban drainage utility
  • Ludwigshafen urban drainage utility
  • Cologne urban drainage utilities
  • Düsseldorf urban drainage utility
  • Magdeburg municipal utilities
  • Leverkusen municipal utilities
  • Burscheid municipal utilities

Comparative Test participants

  • University of the German Federal Armed Forces, Munich, Institute of Water Resources
  • University of Stuttgart, Institute for Sanitary Engineering, Water Quality and Solid Waste Management (ISWA)
  • University of Kassel, Department of Urban Water Management within the Institute for Water, Waste and Environmental Management (IWAU)


Thomas Brüggemann

T: +49 (0) 209 17806-18
E: brueggemann@ikt.de


IKT Comparative Test “Sewer lateral liners 2010”

Overview: Samples from the Comparative Test, showing liners, pipe and escaped resin

Overview: Samples from the Comparative Test, showing liners, pipe and escaped resin

IKT has investigated the material quality and practical usability of CIPP liner products for sewer laterals in the context of an extensive programme of tests. Practically orientated tests performed in the test pipes at the IKT’s large-scale test facility were the focus of this programme. The IKT Comparative Test “Sewer lateral liners” provides drain/sewer operators with reliable and impartial information on the product properties of commercially available refurbishing procedures.


Comparative testing of the quality of refurbishing methods for sewer laterals II


(German versions only)
Table of results, “Standard situation”
Table of results, “Extreme situation”
Test report (188 pages)
Short report (34 pages)


Ministry for the Environment, Agriculture, Nature Conservation and Consumer Protection of the German Federal State of NRW

Participating sewer-system operators

6 x 6 pipess: Layout of the test lengths in IKT's large-scale test facility

6 x 6 pipes: Layout of the test lengths in IKT’s large-scale test facility

  • Stadtwerke Aachen AG (municipal utilities)
  • City of Alsdorf municipal technical utilities
  • City of Bielefeld
  • Bocholt disposal and service utility
  • City of Datteln
  • City of Detmold
  • Düsseldorf urban drainage utilities
  • Stadtwerke Essen AG (municipal utilities)
  • City of Gladbeck
  • Göttingen urban drainage utility
  • City of Hilden
  • Cologne urban drainage utilities
  • City of Lemgo
  • City of Monheim-on-the-Rhine
  • Schwalmtalwerke municipal utilities
  • KOWA Vorsfelde and district water authority
  • Wuppertaler Stadtwerke AG municipal utility


Serdar Ulutaş
Dipl.-Ing. (FH), MBA

T: +49 (0) 209 17806-32
E: ulutas@ikt.de


IKT Comparative Test
“Repair methods for main sewers”

Layout of the test lengths: Pipes with built-in faults

Layout of the test lengths: Pipes with built-in faults

Many waste-water system operators are unsure of what can be achieved by main sewer repair methods and what quality is attainable. Twelve different techniques from the three groups of methods: “Injection/grouting + injection methods”, “Short-liners” and “Internal sleeves” have been comparatively tested under defined and replicable conditions using the IKT Comparative Test “Repair methods for main sewers”. The principal focus was the testing of the techniques in IKT test rigs under conditions approximating to actual practice. The IKT Comparative Test provides reliable and impartial information on the quality of the techniques tested and statements concerning the general suitability of the individual techniques and method groups


IKT Comparative Test “Repair methods for main sewers (DN 200 – DN 600)”


(German versions only)
Table of results
Test Report (155 pages)
Short report (30 pages)
Test Report “Validation of the adhesion properties of short-liners on variously pre-treated substrate surfaces and the use of selected repair methods under external water pressure” (99 pages)


  • Ministry for the Environment, Agriculture, Nature Conservation and Consumer Protection of the German Federal State of North Rhine-Westphalia
  • Environment ministry of the State of Baden-Württemberg
  • City of Dortmund waste-water utility
  • City of Willich waste-water utility
  • Troisdorf waste-water utility
  • Bergisch Gladbach waste-water utility
  • City of Bad Honnef waste-water utility
  • Castrop-Rauxel EUV municipal utility
  • Göttingen disposal utility
  • InfraStruktur Neuss
  • Munich urban drainage utility
  • City of Herford
  • City of Iserlohn
  • City of Oberhausen and WBO Wirtschaftsbetriebe Oberhausen GmbH (municipal utility)
  • City of Plettenberg
  • Düsseldorf urban drainage utility
  • Frankfurt am Main urban drainage utility
  • Hagen drainage utility (SEH)
  • Kamen urban drainage utility
  • Reutlingen urban drainage utility (SER)
  • Cologne urban drainage utilities
  • Minden municipal utilities
  • Espelkamp municipal utilities
  • Stadtwerke Essen AG municipal utility
  • Vellmar municipal utilities
  • Burscheid municipal technical utilities
  • Technische Werke Emmerich am Rhein GmbH municipal technical utilities
  • City of Marl central municipal utility


Serdar Ulutaş
Dipl.-Ing. (FH), MBA

T: +49 (0) 209 17806-32
E: ulutas@ikt.de