A dedicated officer is to be hired in west London in a trial to combat the problem of water-polluting misconnections.
Owing to incorrect plumbing, affected households pump waste into surface drains, which can then spread, killing wildlife and damaging waterways.
Misconnections are illegal, and fixing them is the responsibility of the property owner, external.
Local authorities can take enforcement action, and if the pilot – funded by the mayor of London’s office – is successful, the measure could be rolled out across the capital.
Funding is to be spent where the issue is considered a particular problem, including the River Brent catchment area.
Founder of the volunteer group Clean Up the River Brent (CURB), Ben Morris, said there was “good reason” to think misconnections “are the biggest single cause of pollution in London’s rivers”.
He added: “We need to see stronger action from the councils to get this done.
“They have the power of enforcement and they need to be using those powers to get those property owners to sort out the misconnections.”