The Met is planning to buy three second hand water cannon from German police at an estimated cost of £200,000.
Speaking this morning, Boris Johnson said: "I have concluded there is broad support amongst Londoners for the use of this measure by the police in limited circumstances."
The majority of the 25 Assembly members - including Conservatives - are opposed to water cannon.
More top news
A round the world yacht race set off from London today on a year long journey which will see them circumnavigation the globe.
The shortlist for the ugliest buildings in the country has been finalised with four of them coming from London.
Hundreds of thousands of people turned out for the Notting Hill Carnival today with the weather just managing to hold off.