Sewage Tunnel Step Forward for River Thames

Thames21 welcomes the recent Government announcement (March 22) that a 32.2km tunnel will be built to prevent sewage and rainwater discharges into the Rivers Thames and Lee.

The announcement supports the efforts and dedication of the many thousands of Londoners who volunteer every year to clean up the River Thames and other London waterways.

Around 52 million cubic metres of untreated sewage and rainwater pollute the Rivers Thames and Lee annually - enough to fill the Albert Hall about 525 times - as a consequence of storm overflows.

Sewage in the river degrades river water quality and impacts on wildlife and people who use the river.

Debbie Leach, Chief Executive of Thames21 said, 'It is fantastic news for the River Thames, and for everyone who lives, works or spends their free time along its banks. The tunnel will mean that in the foreseeable future, sewage in the River Thames will be a thing of the past.'

At over 30km long, 7 metres wide and 80 metres deep, this single tunnel is the largest engineering project of its kind undertaken in the UK. The tunnel will run from Hammersmith in West London to Beckton in East London, with an additional spur tunnel from Abbey Mills in Stratford to Beckton.

Thames21 note that surveys indicate the willingness of the public to help fund the construction of the Tideway Tunnel through their water bills. However Thames21 is aware that increases in water bills for some sections of the community will cause concern and that payment arrangements for those on low income should be made as affordable as possible.

For further information visit:

Read the DEFRA parliamentary statement
DEFRA press release
Environment Agency press release
Greater London Authority
Ofwat
Thames Water Press Release

Background Notes

The project is expected to be completed by 2019 - 2020

The sewage tunnel will be 7.2 metres in diametre, almost 40km (25 miles) in length and up to 80 metres beneath the Thames.

It is the biggest engineering project of its kind undertaken in Britain to date.

London has a combined sewage system. This system collects foul sewage at the same time as excess rainwater run-off from roads, roofs and pavements. This waste water is taken to sewage works where it is treated.

Combined sewage systems have limited capacity and during wet weather can fill up. When the system fills up, the overflows discharge into rivers rather than into people's homes.

The Thames Tideway (the Tidal section of the River Thames) has 57 Combined Storm Overflow (CSO) points. It is at these points that combined sewers discharge to the river.

Sewage diluted with storm rainfall is discharged into the River Thames more than once a week on average, around 32 million cubic metres a year in total (DEFRA) - that's 12,800 Olympic swimming pools.

Increased discharge flows into the River Thames result in fish kills, poor water quality, and an increase in 'high risk' days for people who use the river for leisure or work. It is agreed that the environmental impact is negative and worsening with action needed.

The UK has an obligation under the Urban Waste Water Treatment Directive to collect and treat sewage, reduce the frequence of discharges from CSO points and minimise the impact on the enviornment. The Environment Agency has stated that 36 of the CSOs do not meet the requirements of the directive.

Thames21 run up to 50 clean ups on the River Thames every year with volunteers and have first hand experience of the impact - both environmental and aesthetic - of combined sewage outflows. Sewage discharges into the River Thames place an additional burden on Thames21's clean up activities.

Thames21 are particularly concerned with the ever increasing volume of non-organic items contaminating the river such as plastic cotton buds, condoms and sanitary products. These items are initially flushed down toilets and frequently discharged into the river.