What is TDRA?
What TDRA will mean:
- Construction of a large abstraction (water intake) facility on Burnell Riverside (Ham Lands) above Teddington Weir
- Abstraction of millions of litres of water from the River Thames above Teddington Weir to send to the Lea Valley Reservoirs
- Construction of a new outfall (discharge) structure also on the Ham Lands riverside above Teddington Weir (see images)
- Discharge of millions of litres of treated sewage into the River Thames at Teddington
- A 4 year construction time line, 14000 HGVs in the local Burnell Area roads and the open space hoarded off.
- Construction of a 3.5 metre tunnel 4km long under the streets of Isleworth, Twickenham, Teddington, Ham and Kingston to transfer the treated sewage to the outfall
- Construction of a 3.5 metre tunnel to join the abstraction structure to the existing Thames Lee Tunnel (TLT). The existing TLT transfers water to the Lea Valley reservoirs.
- Construction of a tertiary treatment facility on top of the storm tanks at Mogden sewage works (see more details here)
- Thames Water would have a multi million pound asset added to their balance sheet, but we do not think it is the solution for London's water needs.
Click to see the specific impact on Mogden and the new tertiary Treatment Plant and Burnell Riverside Open Space . To read more about this scheme in Thames Water's words, see their website here.
What is TDRA for?
- Thames Water describe TDRA as a 'contingency' asset for drought that will not be continuously in operation
- Thames Water suggests that TDRA may operate every 2 to 3 years and then almost entirely between July and November over their current 47-year outlook plan to 2075
- When not in use as a drought scheme the discharge of treated sewage will operate continually up to 18mld (mega litres a day) 365 days a year to ensure the mechanical systems and filters are kept operational. This is called a "sweetening flow.” The sweetening flow will be discharged from Mogden Sewage Treatment Works in Isleworth.
What is the planning process for TDRA?
In December 2023, Thames Water officially bypassed local planning authority to fast track the scheme through the National Infrastructure planning route. This means they will make the application for development via the Planning Inspectorate.
In Summer 2025 Thames Water launched their Statutory Consultation on TDRA.
In 2026 possibly August or September, Thames Water are expected to make their formal application to the Secretary of State.
Check out our news to see the latest updates
Without action, this plan will go ahead.
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The ‘red line’ boundary shows the areas of land that will be impacted by TDRA during construction. The most significant sites of construction are Mogden, Ham playing fields and Burnell Riverside Open Space.”
The ABOVE GROUND WORKS
The treated effluent tunnel will be 3.5m in diameter and will be constructed under approximately 4Km of South West London. It will require an intermediate shaft at Ham / Playing fields (Richmond). There will be significant above ground works in Mogden Sewage Works (Hounslow) and Burnell Riverside Open Space (Richmond and Kingston). The Burnell Riverside Open Space (Richmond and Kingston) site will be active for at least 21 months. This is because it will be the site of construction of both the outfall and abstraction facilities and 2 shafts.
Read more about impact on those areas by clicking the links below