Tideway, the company behind London’s super sewer, has become the first corporate to issue a ‘Blue Bond’ in Sterling.  

Blue Bonds, a subset of the better-known Green Bonds, are designated to denote specific investor benefits to seas and marine environments. 

Tideway has issued 18 Green Bonds to date, and the ‘blue’ label of the latest issuance showcases the progress on the project with the tunnel now in use and delivering its core benefit of cleaning the river. 

Tideway CFO Mathew Duncan said: “Tideway was one of the first to issue Green Bonds as the project was getting underway, and so it’s great to be building on that legacy with this latest issuance. 

 “With the super sewer now protecting the tidal Thames, including therefore the Thames Estuary and the North Sea, it’s wonderful to be able to offer Blue Bonds in the UK for the very first time. 

“Blue Bonds emphasise the importance of the sustainable use and protection of water resources, highlighting the main purpose of the company – cleaning the river.” 

The Tideway project is designed to intercept the tens of millions of tonnes of sewage pollution that has historically spilled into the Thames each year.  

To date, the Thames Tideway Tunnel, as the super sewer is formally known, has captured more than seven million tonnes of sewage pollution that would otherwise have spilled into the River Thames.    

Since the tunnel was fully connected in February 2025, there have been zero sewage discharges from the spill points to which Tideway connected the new infrastructure.   

The proceeds from this £250 million 8-year blue bond provide Tideway with additional liquidity for the project system acceptance period, which is due to be complete in 2027.