London Fire Brigade was called to a report of flooding at a flat in Archery Close, Wealdstone, on the evening of November 3.
The water was reported to be coming from a flat above the affected home.
Metropolitan Police officers were called to the scene shortly after 8.30pm.
Emergency services forced entry to the flat, where they discovered it was being used as a cannabis factory.
Footage from the scene appears to show a firefighter kicking open the door to the flat before police officers enter.
A police spokesperson said that the cannabis plants and equipment were seized by officers.
Firefighters were able to isolate the flooding and electrics to make the scene safe.
There have been no arrests and police enquiries continue.