London’s super sewer is nearly here – but we must keep making progress

Andy Mitchell CBE, Tideway CEO

The health of our waterways, our seas and our rivers, is fundamental to the health of our country.

People are rightly concerned that not enough has been achieved in protecting these vital natural resources.

However, here in London there is reason for optimism. The new 25km ‘super sewer’ is now 90% complete and will begin testing next year. Live storm flows (raw sewage mixed with rain water) will be diverted away from the Thames, protecting the river for the first time.

Rather than historic storm flows continuing to spill, untreated, into the Thames, they will be diverted through new infrastructure and into the super sewer – and by the time it’s fully operational in 2025, the volume of sewage entering the River Thames in central London will be reduced by 95%.

The impact on the river will be profound. We’ve already seen the ameliorative effect that the Lee Tunnel has had on parts of the Thames’s network – a dozen species of fish thriving in the newly-clean Channelsea River – and looking ahead to this rejuvenation elsewhere across the capital should make everyone in the city proud.

But getting here has not been simple. Sewage pollution is a complex issue and the Tideway project, though an essential part of the solution, is not the panacea.

The super sewer buys us time.

We have concreted over so much natural soakage while at the same time paying little attention to permeable solutions, such as SUDs. In a sustainable world, we need to look at how we reuse and recycle rain, at how housing developments can capture that water for other uses.

When we talk about infrastructure in London, we must not do it on a project-by-project basis. I want infrastructure to be part of a broader conversation, not just about the future infrastructure we may need in the city, but how it is blended with the future needs of London in its entirety.

We also need to look at how we fund vital, new infrastructure.

The Tideway model of private capital, regulatory oversight, and Government contingency support has proved invaluable to the project’s success to date.

Despite the myriad challenges faced during our construction period – Covid, inflation, engineering challenges – the cost of the project to bill-payers remains well within our initial estimates from 2014/15.

What’s more, investing in this project remains an attractive proposition – a fact borne out during our latest £250m bond issuance in July, which was (again) oversubscribed. Getting the project started required some imaginative thinking, including the creation of an independent company with one purpose: improve the health of the River Thames.

I believe that imaginative thinking is key to solving our longterm challenges. Yes, infrastructure must be driven by clear objectives. But it must also be cognisant of its wider context, of its role beyond simply ‘upgrading’ or ‘expanding’. We must consider how our infrastructure impacts on local communities and how it works to create the environments, communities and cities in which we want to live for generations to come.

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