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
Newly re-elected Labour leader Jeremy Corbyn describes his relationship with Mr Khan as "fine", even though they haven't spoken recently.
The kittens were in a poor condition when they were rescued, but are now putting on weight and will soon be ready for new homes.
Ian Bashford was just 200 metres from the finish line when he was struck by the car.