River health
The Thames and its tributaries are the lifeblood of London, shaping communities, sustaining livelihoods and bringing people closer to nature.
Our waterways and wetlands - from the tidal Thames powering through Westminster and Canary Wharf, to the gentle meanders of the Wandle, Lea and Crane - play host to wildlife, homes, transport and leisure. Whether you spend time on the water, travel alongside it, or swim in it, our rivers should be for everyone.
However, for too long they have been neglected and damaged by pollution. Five times more sewage flowed into London’s rivers in 2023, compared to the previous year. Many species are in decline, despite efforts over the decades to restore them.
We’ve started by successfully reintroducing beavers in Ealing and Enfield – and now we want to see London’s waterways teeming with eels, water voles, otters, mayflies and more, focusing on nature-first restorative solutions to increase biodiversity.
Actions we are taking
The Mayor has brought together the crucial partners responsible for London’s water to develop an ambitious 10 year action plan for cleaning up our rivers, starting with a roundtable with key stakeholders such as companies, government agencies, charities and campaigners.
We have asked stakeholders to work with us on the plan and be part of working groups to contribute to that work.
Some themes of work:
- Water Quality - to reduce the pollution entering our waterways which harm our wildlife and people, that want to spend time near, on or in our waterways.
- Access - making it easier for Londoners to access the city’s rivers and spend time in nature, by funding restoration programmes, and opening up new water walkways and locations for Londoners to swim and explore, to help everyone feel welcome in our green and blue spaces.
- Engagement - Londoners and ensure all know the value and benefit of that waterways can provide.
- Biodiversity - Our waterways are home to some fantastic specific of plant and animals and we are working to increase the space and diversity for our wildlife.
Building on London’s progress as the world’s first National Park City, we want everyone who lives in our city to have the chance to experience the well-being benefits of our rivers and waterways.
Useful Maps and Guides
Visit the London River Health map to see what type of sewer system is in your area and the issues facing London's rivers.
You can also view other projects that have been delivered or opportunities that could help improve our rivers on the map.
The new London Outdoor Swimming guide is designed to show you both where Londoners already swim outdoors in the capital and where it could be possible in the future following action by the Mayor and partners.
Water Quality
Read more about some of the key issues facing our rivers:
Inner London. Many parts of inner London have sewer systems that carry rainwater as well as sewage. These Victorian 'combined sewer systems' were designed for a city of four million people. But with sewage from almost nine million people, the network is now at 80 per cent or more of capacity, even in dry weather.
Outer London. Even in parts of outer London where there are separate pipes for carrying rainwater, there are significant capacity and water quality problems.
Sewer (or storm) overflows are a designed feature to prevent sewerage from backing up into homes in the event of exceptionally heavy rainfall. There are more than 100 sewer overflow sites across the capital.
The Urban Waste Water Treatment Directive states that sewer overflows should only be used in “exceptional circumstances” such as extreme weather conditions or exceptional rainfall. However, we are increasingly seeing discharge notifications issued during what many would consider to be normal rainfall events.
That's why the Thames Tideway Tunnel is being built. It will help reduce the amount of untreated sewage that is released into the Thames.
Visit the London River Health map to see the sewer overflow locations in London.
Misconnections are where a property’s wastewater is wrongly connected into rainwater downpipes meaning toilet waste and waste water from dishwashers, washing machines and sinks can discharge into local waterways.
Misconnected properties are a major cause of poor water quality in rivers and can be very harmful to local wildlife.
Plumbing misconnections are usually easy to fix and are the responsibility of the property owner. ConnectRight has further advice on spotting a misconnection and finding a WaterSafe plumber to fix it.
Misconnections tend to be more common in areas where there is a separated sewer system, usually outside of central London which is covered by the capital’s historic combined sewer system (collecting waste water and rain water).
The Zoological Society of London and charity Thames 21 run Outfall Safaris, citizen science pollution monitoring events. The data from these events and data from the Environment Agency has been used in the London River Health map to show where pollution has been reported.
A key source of river pollution is ‘road run off’. This pollution occurs when pollutants that settle on the road build up during dry weather events and are then washed into nearby rivers and streams when it rains. The pollutants get deposited onto the road from residue from oil spills and from tyre and break wear from vehicles.
It has long been one of the most challenging pollution issues to identify, quantify and resolve. A problem that is likely to get worse with a changing climate.
Road Pollution Solutions
The Mayor has partnered with the Environment Agency and the Zoological Society of London to fund Thames21 to develop a new model, which uses numbers and types of vehicles to predict the amount of pollution deposited on roads and the degree of damage to our rivers. The project was also in partnership with Middlesex University, Transport for London, Thames Water and South East Rivers Trust.
Phase 1
The first phase of the study, which took place in 2019, identified roads of varying level of priority that had the greatest potential to contribute towards pollution in London’s rivers. This then helped to identify the best locations for interventions to address this issue. To find out more about phase 1 please see the Road Runoff Water Quality Study Executive Summary.
Phase 2
In 2023, the second phase of the project produced a decision support tool. This tool was created to show varying levels of pollution, and identifies the best locations for nature-based solution interventions to address this issue of road runoff pollution.
The British Geological Survey, as part of the Community Water Management for a Liveable London (CAMELLIA) programme have played a vital part in bringing the underpinning model to life and developing the visualisation for a user friendly decision support tool.
The modelling is limited to the larger roads and rivers as a result of the data available. It is also limited to outer London due to the separate surface water drains present here. The modelling project provides the prediction pollution concentrations for 3,884 km of roads around greater London.
You can access more information about the project with the decision support tool on the Thames21 website.
The results of this project will help to inform further work by the GLA and partners to identify the most appropriate type of roadside sustainable drainage systems and identify new opportunities for wetland creation for priority locations.
These interventions can also provide a host of additional benefits in these locations, including: reducing flood risk, improved amenity, greater biodiversity and localised air quality and cooling benefits. These solutions can be integrated into future highways works.
Access
London’s waterside environments have the potential to be fantastic places for Londoners for recreation, exercise and leisure activities as well as the well being benefits being close to nature. However, more work needs to be done to create access and, thereby, better enable and support these activities.
Currently there is a lack of public access routes or other obstructions, where there are routes, footpaths are sometimes in poor condition creating safety concerns and there is a lack of recreational facilities along these routes. Land ownership can also present as an issue in creating access to waterways.
We aim to address safety concerns, create more equitable access to blue spaces for Londoners, increasing the amount of waterways that are publicly accessible for recreation.
Engagement
As mentioned above, access to London’s waterways is unequal. While we will work to improve physical access to waterways, there is also a challenge in terms of perception.
Only 24 per cent of Londoners think the city’s rivers are clean while 20 per cent of the low-income population and Black, Asian and other minority ethnic communities visit natural areas less than other demographics (16 per cent of Black people and 21 per cent of Asian people). Often, this is because residents do not feel ownership of London’s waterways or do not engage with them.
We aim to empower Londoners by engaging them in citizen science initiatives, and encourage and support their participation in protecting, restoring and using our waterways. We will do this by raising awareness and understanding across all communities of how to protect, care for and enjoy London’s blue spaces.
Biodiversity
None of London’s rivers and streams are in good ecological condition due to habitat loss and species decline. Unfortunately, London’s waterways have not been able to perform their natural processes as these have been compromised by human intervention.
An additional challenge is that historic breaking up and modifications to our blue spaces has meant that rivers are no longer the continuous linear corridors they once were, which hampers the ability of species to move and migrate along these courses.
We aim to restore key parts of London’s river systems to their more natural state, thereby restoring connections and improving ecological and hydrological functions.