A collaborative dialogue between London Waterkeeper and Thames Water
The health of the River Thames has improved dramatically in recent years, but protecting and enhancing it for the future requires genuine collaboration. That’s why Waterscan and The London Waterkeeper have initiated a dialogue with Thames Water to explore how we can go further together. In particular, we’ve asked how green infrastructure can be more effectively integrated into efforts to reduce sewer overflows, and how organisations across the city can contribute to this shared goal. Below, we present both sides of the conversation.
The Future of the Thames: A call for smarter, greener solutions.
by Theo Thomas, London Waterkeeper
The River Thames is cleaner than it has been in a long time. Years of investment, regulation, and environmental efforts have transformed it into a river that now supports wildlife, recreation, and a growing population. This is an undeniable success story—one that deserves recognition. But the work isn’t finished.
Waterscan and The London Waterkeeper are committed to driving forward water sustainability, holding key stakeholders accountable, and collaborating to ensure future progress. The question now is: how can we build on this momentum to make even smarter, greener choices for the Thames?
The Challenge: Green Infrastructure and Sewer Overflows
Historically, Thames Water’s sewer network has struggled to keep up with urban expansion, leading to frequent sewer overflows. While real-time data on these spills is now available—thanks in part to The London Waterkeeper’s successful campaign—reducing them remains a significant challenge.
One of the most promising solutions is green infrastructure. Green roofs, rain gardens, permeable pavements, and other natural interventions can drastically reduce the volume of rainwater entering the sewer system.
Thames Water has made an ambitious commitment to create 7,500 hectares of green infrastructure by 2050, with 99 hectares planned by 2030.
But here’s the challenge: none of this green infrastructure is currently intended to reduce sewer overflows. Why not?
A Smarter Way Forward: Integrated Solutions
If Thames Water is already investing in green infrastructure to tackle surface water flooding, why isn’t it also being designed to reduce sewer overflows?
The potential benefits are clear:
● Cost-efficiency: Combining these efforts would reduce the need for expensive storage tanks and grey infrastructure.
● Environmental impact: Less polluted water entering the Thames means a healthier ecosystem.
● Resilience: Integrated solutions future-proof London’s water management against climate change.
So, we ask Thames Water:
● Have you modelled the impact of integrating green infrastructure into your sewer overflow reduction strategy?
● Can your commitment to green infrastructure go further by incorporating a dual-purpose approach?
● How can businesses, environmental organisations, and communities collaborate with you to make this happen?
Businesses across London have a role to play in shaping a sustainable water future. Here’s how they can contribute:
● Adopt on-site green infrastructure – Rain gardens, green roofs, and permeable surfaces can help reduce stormwater runoff.
● Engage with local water initiatives – Partner with organisations like The London Waterkeeper to advocate for smarter policies.
● Monitor and optimise water use – Working with experts like Waterscan ensures water efficiency and regulatory compliance.
A Call for Collaboration
We’re not here to point fingers; we’re here to drive progress. The Thames is cleaner than ever, and with the right decisions, we can secure its future.
Waterscan and The London Waterkeeper invite Thames Water, businesses, and policymakers to come together, challenge conventional thinking, and champion integrated, nature-based solutions.
Improving the Thames: Blue Rivers, Green Solutions
A response from Thames Water
Mentioning ‘green infrastructure’ when talking about our ‘blue’ waterways can sometimes feel strange for those of us who are passionate about cleaning up our waterways and work every day to improve them.
We’ve already made real progress on the tidal Thames through three phases of improvements since 2010:
Phase 1: £675m upgrade to 5 major sewage works between 2010 and 2015, reducing storm overflows by 40%.
Phase 2: the Lee Tunnel, a £700m investment, was completed in 2016 and took total storm overflow reduction on the tidal Thames to 55%.
Phase 3: £4.6bn Thames Tideway Tunnel project will become fully operational in 2025 and will take the cumulative reduction in discharges to 95%.
More green spaces = less storm overflows
More though needs to be done and Theo Thomas is right to identify the role that green solutions play in improving our blue spaces.
The single biggest driver of storm overflows is the volume of rainwater entering our foul wastewater sewers.
In heavy rainfall, the runoff from a single misconnected patio (where the storm water drains to a foul sewer) can contribute the same volume of flow to the sewer network as the wastewater from 100 homes.
Alongside reducing the number of misconnections, sustainable drainage systems (SuDS), green spaces in urban developments that provide a natural alternative to rainwater runoff, provide a solution for preventing rainwater which otherwise would enter the sewer network and cause flooding and storm overflows.
This challenge will be significant.
We estimate that over 7,000 hectares of impermeable area need to be disconnected from draining into our sewers by 2050, the equivalent of 10,500 football pitches.
Collaboration is key
We have just announced £1.8bn worth of investment in London over the next five years as part of the fourth Phase of our plan to help improve London’s rivers.
It will add to the 95% reduction in overflows into the tidal Thames since 2010 and go further by focusing on the Thames’ tributaries, including tackling overflows on the Roding, Wandle, Lee and Brent.
In London, we have joined forces as part of the Mayor’s Clean and Healthy Rivers Roundtable to support collaboration and build on the success of our Smarter Water Catchment pilots.
In 2020 we launched our Smarter Water Catchments programme, including on the River Crane, alongside charities, community groups, local councils and government agencies.
This was a completely new approach. Instead of working in isolation, the different actors in the catchment co-created, co-designed and are now co-delivering a ten-year action plan.
This work has meant that the River Crane is now recognised as the river in North London most likely to achieve ‘good ecological status’, a result of the successful collaborative work that is being done there.
To build on this success, we have announced a £20m fund for environmental and community groups, so we can work together to deliver more of the sorts of benefits we’re seeing on the Crane and increase collaboration with all partners involved in river health.
How to increase green spaces
By their very nature, the interconnectedness of our blue spaces and rivers means that ultimately, no one organisation can improve them alone.
The success of our Smarter Water Catchments programme shows the success that can be achieved by multiple partners working together to achieve ambitious collective outcomes.
Green infrastructure is another area where more needs to be done by everyone involved, but we need the government to ensure that the right frameworks are in place.
The case for embedding SuDS into new developments has been clear for over a decade, which is why it was included in the Flood and Water Management Act 2010 and would have required permeable green spaces in new developments.
However, the relevant parts of the Act have never been brought into force, meaning that opportunities for embedding permeable green spaces into our urban areas have been missed.
Ultimately, to truly improve our blue waterways, we need to think more about the impact that the loss of green spaces has and work collaboratively to restore them into urban environments.
A Shared Path Forward
This dialogue demonstrates that progress on river health doesn’t come from one organisation alone: it comes from cooperation, challenge, and joint ambition.
Waterscan is proud to support this conversation between The London Waterkeeper and Thames Water, and we believe it sets the tone for the kind of transparent, multi-stakeholder action needed to secure a more resilient, sustainable Thames for the future. We look forward to continuing this collaborative journey.
Water Matters 2025
These crucial topics will be a highlight of the day at Water Matters 2025 with Theo Thomas, CEO, London Waterkeeper, Helena Soteriou-Hains, Head of River Catchment Strategy, Thames Water and Andrew Tucker, Water Demand Reduction Manager, Thames Water all taking centre stage.
Places are going fast for the premier platform for shaping the future of the water industry, Water Matters brings together leaders ready to act. This year, we deliver outcome-driven insights that empower organisations to make meaningful strides in water stewardship. The need to act is no longer a question – it’s a must. Our focus is on how to act, providing clear, practical roadmaps that drive immediate and impactful results in sustainable water management.
Register today > and connect, learn, innovate.
