The Thames Tideway Tunnel will be a new "super sewer", the width of three London buses, which will run underground from west to east London.
It will be around 20 miles long - and will broadly follow the route of the River Thames, connecting up to 34 sewer overflows.
Sewage, which would otherwise spill into the River Thames, will then be captured in the new tunnel and transferred to a waste water plant in Beckton to be treated.
More top news
Members of the RMT union will walk out in a row over the role of conductors, causing fresh misery for hundreds of thousands of passengers.
The five year long jail sentence of a London mother held in an Iranian jail has been upheld.
Barnet police are investigating four separate anti-semitic offences in the last two days