The Burroughs in Hendon will remain closed until Wednesday evening, according to Thames Water.
In a statement the water company explained: "Due to the extensive damage caused by this burst pipe, we will unfortunately be unable to reopen the road before Wednesday evening.
“A large area of the road has been damaged and the concrete that will need to be poured in to the hole to repair it will take at least 24 hours to set.
“We will then need to resurface the road and allow that to set.
“We are really sorry for the disruption this is causing but it is important that drivers do not ignore the closure and try and drive along the pavement as this is dangerous and is putting lives at risk."
Thames Water engineers were initially called at 1am following reports of a burst water main.
They repaired the original leak by 6am but another pipe then also sprung a leak.
As a result of the disruption traffic is congested in Church Lane, Brent Street and The Burroughs.
Transport for London has confirmed that bus routes 143, 183 and 326 have been affected.