Stadtwerke München Tests Single-Well System

July 20, 2026

Source: E & M Powernews

A pilot plant for a single-well system is being built in Munich-Pasing, designed to enable groundwater heat pumps on small properties and reduce investment costs.

In Munich-Pasing, the Technical University of Munich (TU Munich), Stadtwerke München (SWM), the City of Munich, and the company Baugrund Süd are constructing a pilot plant for a single-well system for groundwater heat pumps. The facility is intended to demonstrate whether the system is a viable alternative to conventional two-well solutions.

The site is the “Haus für Kinder” daycare center on Oselstraße, which cares for about 100 children daily. Groundwater monitoring stations have already been installed there, and pumping tests have been conducted. Two single-well systems with different designs are currently being built and will be compared with each other as part of the pilot project.

The project was initiated due to the limited space available on many properties. According to the project partners, about one-third of urban and private properties in Munich are too small to accommodate the two wells typically required for groundwater heat pumps, spaced at the necessary distance. The new system, however, requires only a single well location.

In conventional groundwater heat pumps, water is extracted through one well and returned to the ground through a second well. The single-well system combines both functions in a single borehole. An internal seal is designed to prevent the cooled water from immediately re-entering the extraction well.

Significantly lower costs

Kai Zosseder from the Chair of Hydrogeology at the Technical University of Munich explains: “What makes our system unique is that both the extraction and reinjection of groundwater take place through a single well. An internal seal prevents cooled water in the well from flowing directly back into the extraction zone.” The relatively high natural flow velocity in the groundwater prevents this from happening on a larger scale within the aquifer, according to the scientist.

According to the project partners, the single-well system is about one-third less expensive overall than a system with two wells.

SWM views the project as a complement to its heating transition strategy. “With the single-well system, we’re opening up the opportunity to make groundwater heat pumps feasible and affordable for a significantly larger group—and thereby noticeably accelerate the heating transition as a whole,” Karin Thelen, Managing Director of “Regional Energy Transition” at SWM, is quoted as saying in a joint press release.

Comparing Two Variants

The pilot project is examining two technical variants. One design uses two parallel pipes within the borehole for water extraction and injection. The second variant relies on a pipe-in-pipe system that requires smaller borehole diameters.

“The drilling will be completed within about a week,” explains Manuel Gossler, project manager at SWM. The pilot project will determine which construction method is more suitable and easier to implement in practice.

The testing will be scientifically monitored. Plans include temperature and water level measurements, as well as tracer tests to investigate groundwater flow conditions. The tracer tests are scheduled to take place in 2026. The entire system is scheduled to go into operation in 2027, following the completion of the heating system conversion. The system will then undergo scientific evaluation through 2029.

Author: Manfred Fischer