Fines for people that don't recycle looked increasingly likely this week after 16 Barnet households received formal warnings.
The properties, in the Totteridge ward, have been subject to compulsory recycling since April 2004, but have yet to make use of their recycling bins.
A Barnet council spokesman said: "The households have received two letters and a personal visit but still aren't using their black boxes.
"If they fail to respond to this, we will issue a section 46 notice and failure to comply with this will lead to legal proceedings."
Barnet council ran a pilot compulsory scheme across 21,000 households from April last year.
Following its success in boosting recycling rates by 18%, the compulsory scheme was rolled out across the London borough's 113,000 homes on March 1 this year.
Barnet has yet to take legal action against anyone for failing to recycle, but if these 16 offending households are taken to court, they could each be fined up to £1000.
"However," the council spokesman added, "if they start recycling today everything will be dropped".