Municipal sewer networks are under growing pressure. Ageing assets, increasing capacity demands, and tighter environmental standards are driving rehabilitation programmes that need to deliver results without tearing up roads and disrupting communities. Trenchless sewer repair makes that possible by rehabilitating the host pipe from the inside, with no open-cut excavation required. Insituform invented this approach in 1971 and today manufactures CIPP Felt, the liner system at the heart of municipal sewer rehabilitation programmes worldwide.
The Trenchless Approach to Sewer Rehabilitation
Traditional dig-and-replace requires excavating the full length of a damaged sewer, removing the old pipe, laying a new one, and reinstating the surface. For municipal networks running beneath busy roads, footpaths, and populated areas, that approach comes with significant cost, disruption, and programme risk.
Trenchless sewer repair takes a fundamentally different path. A resin-saturated liner is inserted into the existing pipe and cured in place to form a new structural pipe within the old one. The host pipe stays in the ground, the surface stays intact, and the rehabilitated sewer is returned to service in a fraction of the time.
For municipal engineers managing large rehabilitation programmes, this means shorter traffic management windows, less disruption to residents and businesses, and the ability to rehabilitate longer sections in a single operation. It is a practical, proven method that has been used across trenchless pipe repair projects globally for over 50 years.
How CIPP Felt Rehabilitates Sewers Without Excavation
CIPP Felt is the liner system we originally developed for gravity sewer rehabilitation, and it remains our most widely specified product for wastewater and stormwater networks.
The process is straightforward. A felt liner, pre-impregnated with resin at our manufacturing facility in Wellingborough, is delivered to site and inserted into the host pipe via inversion. Once positioned, the liner is inflated against the pipe wall and cured using hot water or steam. The resin hardens to form a continuous, jointless thermoset pipe bonded tightly to the host pipe profile.
What makes CIPP Felt particularly well suited to sewer rehabilitation is its versatility:
- Covers diameters from 70mm to 2,500mm, from lateral connections through to major trunk sewers
- Compatible with any host pipe material
- Handles bends up to 90 degrees and conforms to complex profiles, including egg-shaped sewers
- Provides the least cross-sectional reduction of any sewer rehabilitation method, preserving hydraulic capacity
- Can be delivered impregnated for Western European projects or dry for worldwide supply
Single CIPP Felt installations from 50 years ago are still in service today. That kind of proven longevity matters when you are specifying for assets that need to perform for decades. For a closer look at how CIPP lining applies across water and sewer pipes, we have covered the detail in a dedicated article.
What Trenchless Sewer Repair Delivers for Municipalities
The benefits of trenchless sewer repair go beyond avoiding excavation. For municipal programme managers, CIPP Felt delivers a set of practical advantages that shape how sewer rehabilitation projects are planned, specified, and delivered.
Minimal surface disruption. CIPP lining requires access only at existing manholes. Roads stay open, traffic management is reduced, and the impact on surrounding communities is kept to a minimum.
Faster project delivery. Recent sewer rehabilitation projects in Kassel, Losheim am See, and Leipzig show what trenchless rehabilitation can achieve on tight timelines. In Kassel, 127 metres of complex egg-profile sewer were rehabilitated in five days. In Losheim am See, 605 metres of DN 300 sewer were completed in the same timeframe.
Lower carbon footprint. Avoiding excavation removes the need for heavy plant, spoil disposal, and new pipe materials. Our CIPP Felt liners are manufactured with 75% recycled material, and we recycle 90% of waste from the manufacturing process.
Extended asset life. CIPP lining restores full structural integrity and seals against infiltration, root intrusion, and exfiltration, extending the service life of the rehabilitated sewer by decades.
Specifying CIPP Felt for Sewer Infrastructure Renewal
For consulting engineers and specifiers, the quality of the liner system is the foundation of a reliable specification. Here is what sets Insituform CIPP Felt apart.
Manufacturing standards. Every CIPP Felt liner is produced under ISO 9001:2015 certification. We apply 28 quality control checks for every single CIPP liner, with full traceability from raw materials to dispatch.
Scale and availability. We manufacture 1 million metres of CIPP lining per year on average, supplying projects worldwide. That scale means consistent product quality and reliable lead times, even across large, multi-phase rehabilitation projects.
Sustainability credentials. 75% recycled material within our flagship products, with 90% of manufacturing waste recycled.
People. Our team operates with 0% staff turnover, except for retirement. The specialists manufacturing your liner are the same people who have been refining the process for years.
For a broader look at rehabilitation methods and how to match the right approach to your project, see our engineer’s guide to pipeline repair.
The Liner Behind Sewer Rehabilitation
Trenchless sewer repair has become the go-to method for sewer rehabilitation, and the liner at the centre of the process determines how well the asset performs for the long term. Insituform CIPP Felt has been delivering that performance for over 50 years, for municipalities and contractors across sewer networks of every scale and complexity.
Explore CIPP Felt to see the full product specification, or speak to our technical team about your next rehabilitation project.
