Why we object to Thames Water's TDRA

This campaign opposes Thames Water's TDRA scheme on environmental and social grounds.

The TDRA scheme is environmentally flawed

There will be a clear environmental and ecological impact on the River Thames. Green spaces are protected for a reason: for the protection of nature and for the benefits that access to nature can have on human health.

  • The plan will abstract (remove) water from the River Thames at a unique location where the tidal river meets the freshwater river.
  • This water will be replaced with treated sewage year round — every hour of every day. This is because to keep the mechanics, shafts and pipes clear, the scheme must run treated sewage into the river at 25% of capacity year-round. This is called a "sweetening flow."
  • There will be a significant impact to putting treated sewage into the River Thames. See details below.
  • There will be trees chopped down
  • There will be badger setts disturbed
  • Building compounds will cause earth compaction and change the soil biome
  • Building compounds will interfere with the natural movement of mammals and birds which may damage their ability to flourish.

"In addition to the potential traffic impact, it is likely the TDRA would have a substantial negative impact onthe ecology of the Metropolitan Site of Special Interest for Nature Conservation that comprises Ham Lands. While I can acknowledge Thames Water’s stated commitment to biodiversity net gain and reconstruction, this does not discount the immediate impact the temporary destruction of acres of nature reserve would have on local flora and fauna. Once mature trees are felled, they cannot be replanted, and once badger setts are destroyed, and their occupants killed or driven off, they cannot necessarily be restored. These are two specific examples of the damage this project could do to the area, but Thames Water’s own documentation cites a potential impact on a wide array of wildlife."
Sarah Olney, MP for Richmond Park. Letter to Constituents, November 2023,.

The TDRA scheme is socially flawed

To construct the tunnels, shafts outfall and abstraction sites, Thames Water will be removing land from community use for a significant period of time, causing a high social cost.

Specifically in Ham Lands and Burnell Open Space

  • The North Kingston construction site includes the pipeline shaft, the discharge structures, the abstraction structures and the connection shaft to the TLT tunnel. This means virtually the whole of Burnell will be a building site.
  • In just over a mile (from near Ham House in the north to the Hawker Centre YMCA in the south) TDRA will mean the construction of five 10.5 metre shafts along with the new pipeline.
  • The Burnell open space at the south of the scheme will be hoarded off for construction of the outfall structure and abstraction structure, as well as several ancillary kiosks.
  • There are several primary and secondary schools within the area of construction along with thousands of residents
  • Every day, there will be a huge impact on the thousands of walkers, runners, casual river users and swimmers that use the Burnell Open space and the Thames Path National Trail towpath.
  • Some of the roads in Ham Lands can barely accommodate two cars at the same time. The more densely built areas of Isleworth and Moormeads will also suffer from extra thousands of HGVs and other construction traffic needed to build the new treatment facility at Mogden.

Specifically in Moormead:

  • Created from wasteland, this lively park now plays host to a number of sports and community events and has a pleasant village green atmosphere. The park has numerous facilities including a children's playground, football facilities and tennis courts. All will be impacted during a long construction period.
  • Local schools that do not have their own playing fields rely on Moormead Park to provide areas for sports.

Throughout residential neighbourhoods

  • Construction will take place on roads that were never built for, and cannot sustain, continuous heavy construction traffic of the kind TDRA will require.
  • Construction of each shaft may need 26 HGVs a day over an 8-month period.
  • There will be issues of noise, air quality, building vibration, nighttime working, and construction traffic.
  • The tunnels will be going under conservation areas with buildings that are already subject to subsidence. Many people in the areas of the conveyance route and the construction are very concerned about the impact of pipejacking under their houses, the impact of shaft construction vibration on their properties and also the sheer amount of construction traffic. These issues need to be addressed by Thames Water. There was no information for residents at the information events, despite Thames Water referring concerned residents to attend those meetings to get their questions answered.

Thames Water cannot be trusted

Thames Water claims the TDRA proposal will be safe, as they are regulated and are required to adhere to regulations dictated by the Environment Authority and other bodies.

However, campaigners are concerned that these regulations are insufficient to protect the river. And, further, that although fines may be imposed for breaches, this is not enough to protect our river.

Thames Water has indicated they do not plan to make the river worse with this scheme.

"We’re committed to ensuring that water quality of the River Thames is not deteriorated as a result of the Project."
Thames Water, p.10 Teddington Direct River Abstraction and Water Recycling Project, October - December 2023.

But, Thames Water's record is poor

Thames Water has repeatedly put profits and shareholders ahead of customers and the environment.

Prosecutions of Thames Water by the Environment Agency for pollution incidents have now led to fines of £35.7m between 2017 and 2023.

"Whilst there is undoubtedly a need to future-proof our water supply, there is a fundamental issue around trust. Thames Water has a terrible record — regularly spilling raw sewage into our rivers and losing a quarter of its water supply every day due to leaks — whilst rewarding its executives with sky-high bonuses."
Munira Wilson, MP for Twickenham. Letter to Constituents, November 2023,.

Water and sewerage companies in England: Environment Agency's environmental performance report 2022

In this summary report on the environmental performance of the nine water and sewerage companies operating in England from the Environment Agency, Thames Water was given a two-star rating.

Further, in reporting the total number of water pollution incidents, the EA reported that Thames Water performed "significantly below target (red)" for the EPA metric that assesses the total number of water quality pollution incidents from sewerage assets.

A film about Ham Lands

This video was created by local Kingston resident Maddy, a final-year student at Manchester University. She created this video as part of her university work. Her focus was to showcase the biodiversity and importance of Ham Lands and how destructive the Thames Water Teddington River Abstraction Scheme would be.

Learn how Ham Lands was created — on gravel pits filled with topsoil (and seeds) from all over London — and why it matters to save the area from any disruption.

The impact of putting treated sewage into the River Thames

Impact on plant life of treated sewage in river water

The Environment Agency has enforced 'nutrient neutrality' for the effluent outfall. These nutrients consist mainly of Nitrogen and Phosphorus, well known to gardeners as they're added to commercial compost and fertilisers in specific amounts to promote plant growth.

The undiluted presence of these in raw sewage damages aquatic plants, causing some species to thrive and become invasive and others to die, compounding the wider river ecosystem.

This is why the Environment Agency is requiring Thames Water to filter out these nutrients to appropriate levels.  This is also why Thames Water is saying the effluent outfall ‘will not make the river any more polluted.'

Impact of chemicals in treated sewage in river water

Currently, the Environment Agency does not regulate chemicals that Thames Water is not filtering from the treated sewage going back into the water.

Thames Water has confirmed they will not be removing pharmaceuticals such as hormones, painkillers and antibiotics. They will also not be removing microplastics or emerging contaminants (also known as forever chemicals) like PFAs and PFOs. These are suspected as carcinogenic and derived from cleaning products and the manufacturing industry.

Risk of faecal contamination by putting treated sewage in river water

Currently, Thames Water is not obliged or planning to reduce the presence of bacteria, viruses and parasites from the effluent, which would include faecal contaminants such as E. coli, salmonella and coronavirus. A decision will be made in 2025 as to whether these will be reduced.

The concentration of all these contaminants when the effluent outfall is flowing at 75 million litres a day will be greatly concentrated because the abstraction plant will be removing 75 million litres of fresh river water a day and the river will be at its lowest due to drought. At this time river users will be at their peak, especially children.

Swimmers at the proposed outfall location are already suffering the effects of microbiological pollution from raw sewage spills. The effects of emerging contaminants on human and aquatic life are more unknown, though we will be producing a report compiling existing research on this to present to Thames Water in due course.

Thermal load and salinity impacted by putting sewage in river water

The natural water temperature of a river is increased when treated effluent is added. Treated effluent is warmer than river water.

The salinity (salt content) is also increased when treated effluent is added.
Increasing the temperature reduces dissolved oxygen and increases the metabolism of cool- and cold-water fish, causing them to burn energy at a faster rate and result in death when river temperature exceeds their physiological limits.

Salinity plays an important role too as it impacts growth rates and metabolism. For some fish higher salinity is beneficial but for others, it’s incredibly detrimental.

bluetits at abstraction point

Swimmers at the proposed abstraction (removal) location on the river.

The Blue Tit swimmers in the River Thames.

The Blue Tit swimmers in the River Thames.


Ham Lands adjacent to Riverside Drive. Location of one of the shafts and months of construction work and hundreds of heavy good vehicles. (Photograph courtesy of R James.)

The proposed site at Moor Mead Park. (Click for a larger image.) (See Thames Water's map book for more maps.)

Link to a video walk through on Facebook over Moor Mead Bridge and into the park, showing the areas that will be impacted by the scheme. (Video courtesy of W Flower.)

Link to a video walkthrough on Facebook of the areas that will be impacted by the TDRA on Burnell Open Space and Park Gate Woods. (Video courtesy of B O'Dea.)

Link to a video walkthrough on X / Twitter of the areas impacted by the TDRA on Park Gate Woods. (Video courtesy B O'Dea.)

Proposed shaft site on North Riverside Drive in Ham. (Click for larger image.) (Photograph courtesy of B O'Dea.)

Moor Mead Park. A park used every day for recreation by residents and school children.

Park Runners in Moormead. Every weekend, juniors (4 to 14 years old) use Moormead Park for a 2K run.

Location of the discharge site along the riverside

Location of the discharge site

The propsed site of Shaft 6 in Ham Lands

Park runners in Burnell Open Space. Every weekend, around 350 Park Run participants join a 5K Park Run starting on Burnell Avenue and continue towards Teddington Lock along the tow path, returning back along the river and finishing at the YMCA Hawker Center. Under new TDRA plans this run would become impossible.

River from the Burnell Open Space

Every day, thousands of people use this stretch of the River Thames for recreation.

During the march against the TDRA in the summer of 2023, many joined our protest.

Proposed shaft site on North Riverside Drive in Ham. (Click for larger image.) (Photograph courtesy of B O'Dea.)