Thames Tideway Tunnel: CSO Diversions

Mariners are advised that constructors for the Thames Tideway Tunnel are in the process of connecting the tunnel to new combined sewers at seven sites on the Thames. 

During this process there will be a period where the new combined sewers are not connected to, or are only partly connected to, the Tunnel. This means that any rainwater and raw sewage which would normally be collected by the Tunnel and transferred to a treatment plant at Beckton may instead discharge directly into the river at these sites. 

It is expected this period will be in effect until the middle of 2025. 

The seven sites and their associated Notice to Mariners are:

If no Notice to Mariners number is associated with a site this means that it has not yet been connected to the warning system. This Port Wide Notice will be updated regularly as new CSO sites are diverted. 

CSO discharge alerts and warnings will be broadcast by London VTS on Ch 14. Additionally, notice of discharge will be issued by the PLA as a Navigational Warning on the website, via Notice to Mariners email distribution lists and on X.  

Mariners should pay attention to warning lights and exercise caution when navigating in the vicinity of these sites.