What will be the benefits of the Thames Tideway Tunnel?

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The Thames Tideway Tunnel will prevent millions of tonnes of sewage entering the river Thames, meaning cleaner water for river users and a healthier environment for wildlife.

London’s Victorian sewage system is currently discharging millions of tonnes of sewage into the Thames every year. The new “super sewer” will intercept at least 94% of this volume in a typical year. Importantly, the tunnel will capture all of the ‘first flush’ from the sewers after heavy rain.  This contains all the sediment that has built up during periods of drier weather and causes the most damage.  

So, instead of over 50 sewage spills a year, there will only be three or four, mostly surface water runoff after heavy storms. The tunnel will also capture unsightly floating sewage litter, including wet wipes which don’t break down, and are now building up in large mounds in slow-flowing stretches of the river

This will immediately make the Thames much cleaner, with huge health and aesthetic benefits for everyone who uses the river – now and for generations to come.

Rowers and anglers won’t get ill as a result of water splashing into their faces, and parents will be able to let their children feed the ducks from the foreshore without fear of tummy bugs.

Cleaner water for people will also mean a healthier environment for wildlife. As part of the Thames estuary, the tidal Thames can already support a range of fish species through different stages of their life cycle. When the Thames Tideway Tunnel starts operating in 2024, far fewer fish will be killed as a result of low oxygen levels in the water, and the Thames will be able to take its rightful place as one of the most important nursery areas for North Sea species. Many kinds of water birds will benefit from better populations of fish, and we can even look forward to seeing more porpoises, dolphins and seals in the middle of our capital city.

There’ll be plenty of economic advantages too. For instance, more than 4,000 jobs will be created while the tunnel is being built, with several thousand more jobs in the supply chain and the wider economy. At least 25% of employees will live in the boroughs where the work sites are located with the wider economic benefit spread across the UK.

Rejuvenating London’s river-based economy will be another important benefit of the Thames Tideway Tunnel. Protecting the River Thames ecosystem will help to sustain commercial fishing industries, and a cleaner River Thames will enhance London’s reputation as a business centre and tourist destination.