Visiting the Scottish Water control room where the country’s vast network of pipes and sewers are managed, Ms Cunningham said the tunnel built on the legacy of the country’s engineering and water pioneers and would benefit communities for centuries to come.

Flows have started to run through the tunnel from across the south-side of Glasgow with communities expected to benefit from fewer flooding incidents and improved environmental conditions.

Ms Cunningham said: “The strategic importance of the Shieldhall Tunnel as part of the ongoing investment across Glasgow by Scottish Water cannot be understated. It’s a fantastic example of the capital investment programme delivering real long-term benefits for communities to reduce flooding, help deal with the impact of climate change and improve the environment.

“Much of our underground infrastructure for water and waste water dates to the Victorian era when we proudly led the way in introducing massive improvements to deliver positive impact on the health of our communities. Communities across Glasgow will benefit for years to come from this latest extraordinary feat of engineering which lies hidden deep beneath the city.

“It represents the latest chapter in our collective aim to provide safe and sustainable ways of managing waste in our biggest city. It is a significant part of the overall investment in Greater Glasgow which is essential to economic prosperity regionally and nationally. Scottish Water is investing £3.5 billion throughout the country to deliver infrastructure which is fit for communities now and for decades to come.”

The tunnel is the flagship project in Scottish Water’s investment in the Glasgow area’s waste water infrastructure, the biggest since Victorian times, and stretches for 3.1 miles from Craigton to Queen’s Park via Bellahouston and Pollok parks.

It was constructed over almost two years by a team of more than 100 workers, from countries across the world, using a state-of-the-art tunnel boring machine (TBM) named Daisy the Driller by a local schoolboy, which weighed 1000 tonnes and was longer than 14 buses.

The tunnel will alleviate pressure on the existing waste water network with 90,000 cubic metres of extra storm water storage. That’s more than 108m litres or the equivalent of 36 Olympic-sized swimming pools.

It will also reduce the risk of flooding in Aikenhead Road and Curtis Avenue in Mount Florida and Robslee Drive, Robslee Road, Robslee Crescent and Orchard Park Avenue in Giffnock.

Some of the key facts and figures about the £100 million tunnel include:

The tunnel will substantially reduce the amount and frequency of waste water discharged from a number of Combined Sewer Overflows (CSOs) and enable more than 90% of what was discharged at these CSOs to be treated at Shieldhall Waste Water Treatment Works before being discharged there.

Douglas Millican, Scottish Water’s chief executive, said: “We are delighted to have completed the Shieldhall Tunnel, which is the flagship project in Scottish Water’s investment in the waste water infrastructure in the Greater Glasgow area – the biggest in well over a century.

“The city’s waste water infrastructure required major improvements to help transform it into a modern, integrated and sustainable system which will improve the environment and biodiversity on the River Clyde and help tackle flooding.

“As the Greater Glasgow area continues to develop, we are modernising our waste water infrastructure to support the needs of both existing and future customers.

“The completion of the Shieldhall Tunnel is a key part of that network modernisation.”

Dominic Flanagan, Scottish Water project manager, said: “Many hundreds of people have worked as part of Costain VINCI Construction Grand Projets (correct) Joint Venture (CVJV), which was set up to deliver the tunnel.

“To enable the construction of the tunnel required a wide range of specialist skills, knowledge and expertise. Over the course of the project, our workforce has included local contractors and those with international experience and backgrounds.

“We are all enormously proud of what we have achieved for the good of the people of Greater Glasgow.”

Neil Grosset, the project director, of Costain, said: “Everyone in the Costain and VINCI Construction Grands Projets team is delighted to have delivered the Shieldhall Tunnel project for Scottish Water and the people of Glasgow. Completing this scheme, one of the most challenging of its kind in history, is testament to the passion, skills and team spirit of everyone involved in the project. The Shieldhall Tunnel is infrastructure that will have a huge positive impact, reducing the flooding risk and improving the environment for the people of Glasgow and the River Clyde now and in the future.”