Munich, April 9, 2026 – A remarkable engineering project is currently underway beneath Lilienstrasse, in front of the Mariahilfkirche in Munich. The Münchner Stadtentwässerung (MSE – Munich City Drainage) is undertaking a complex, 2.5 million euro renovation of a 135-year-old, 220-meter long sewer channel, one of the oldest in the city, without the need for extensive street excavation.
A Historical Underground Marvel from 1889
The sewer channel, located between Mariahilfplatz and Kreuzplätzchen, dates back to 1889. Constructed from double-layered canal bricks, the man-sized pipe features a clever egg-shaped profile – wider at the top and narrower at the bottom. This design ensures a consistent flow rate, even with low volumes of wastewater, minimizing sediment buildup.
Thousands of Munich households from Au, Giesing, Geiselgasteig, and the southern districts east of the Isar River still rely on this historic channel. It crosses beneath the Isar near the Ludwigsbrücke, close to the Deutsches Museum, and continues northward to the Gut Großlappen sewage treatment plant.
Innovative “GRP Short Pipe Lining” Method
After 135 years of service, the section of the channel under Lilienstrasse requires extensive renovation. Experts are employing a sophisticated engineering technique called “GRP short pipe lining.” This method involves inserting modern, egg-shaped glass-reinforced plastic (GRP) pipe sections into the existing historic brick channel through a single excavation pit at Lilienstrasse 66.
Each GRP pipe section measures between 1.8 and 2.3 meters in length and weighs up to 800 kilograms. These segments are precisely connected after being pushed into place. The MSE team installs 48 pipe sections weekly, working first southward and then northward in the direction of flow. In total, 106 sections will be joined along the 220-meter stretch, with a final connecting pipe piece closing the gap.
Above-Ground Wastewater Diversion Minimizes Disruption
During the renovation, wastewater from the affected districts continues to flow, thanks to an ingenious above-ground diversion system. A “vacuum suction pump system” redirects the wastewater through large blue pipes elevated up to 4.5 meters above Lilienstrasse. This temporary pipe network ensures that access roads, sidewalks, and emergency routes remain clear, minimizing disruption to residents and the environment. The MSE emphasizes that this method is not only efficient but also environmentally friendly and considerate of local residents.
Project Completion Before Maidult Festival
The construction work in Lilienstrasse is expected to conclude on Friday, April 24, just one day before the start of the Maidult festival at Mariahilfplatz on April 25. This timely completion ensures that the popular annual event will not be impacted by the ongoing renovation.
Munich’s Extensive Sewer Network
The Munich sewer network spans an impressive 2,436 kilometers, with sections constantly requiring renovation. In 2024, the Münchner Stadtentwässerung renewed 33 kilometers of pipe channels and 2,500 meters of walkable channels. Future projects include the renovation of a 770-meter brickwork channel in Schellingstrasse.
Source: https://www.abendzeitung-muenchen.de/muenchen/spektakulaere-sanierung-unter-der-erde-ein-stueck-muenchner-ingenieurskunst-art-1123988
