MGjv, a joint venture between Galliford Try and M Group Water, is building the Southampton Link Main, a 19km drinking water pipeline, for Southern Water.
The new underground pipeline will run from Otterbourne to Yew Hill reservoir, near Winchester, and then south to our Rownhams water supply works on the outskirts of Southampton.
As part of the project, a manually operated tunnel boring machine (TBM) is helping to dig tunnels
The TBM, called Ancasta, weighs 6,500kg, is 2.7 metres long and is forming a 1.5-metre-wide tunnel. The pipe depth starts at 14 metres. The tunnel work started in September 2025 and will continue through to May 2026.
Ancasta is one of two manual TBMs that are in use on the project.
The whole Southampton Link Main project will take more than three years to complete and cost more than 拢100m. Most of the pipeline will be laid by digging trenches, installing the pipeline and then backfilling them with earth. However, in some areas, it will be installed by digging tunnels deeper underground to avoid disruption to major roads, railway lines or precious ecological sites.
Southern Water major projects director Ben Ring said, 鈥淭he Southampton Link Main project has been under way since the middle of 2025 and there are many exciting aspects to major projects such as these. This is part of a wider set of projects designed to improve the resilience of our water network for our customers in Hampshire. The project will also provide future resilience for the Test and Itchen rivers and their wildlife.鈥�
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