A campaign has been rolled out in Brent warning residents they risk their homes being flooded with raw sewage by throwing leftover cooking fat down the sink.

Blocked pipes caused by the practice has resulted in gardens and even the homes of 628 addresses in the borough being flooded in the last five years, according to Thames Water.

The borough has been recognised as one of the worst affected by fatbergs - congealed lumps of leftover cooking fat which cause the blockages.

Almost 8,000 fatbergs have been cleared in Brent in five years compared to 7,000 across the entire county of Oxfordshire.

Wet wipes being flushed down the toilet instead of being thrown away are also being blamed.

Thames Water have launched a widespread advertising campaign to raise awareness of the problem in Brent and five other badly affected boroughs Richmond, Hillingdon, Harrow, Ealing, and Hounslow.

The adverts on billboards and bus stops, urge customers to ‘bin it – don’t block it’.

Trevor Hennessey, sewer operations manager for West London, said: “Absolutely no one wants to have sewage overflowing into their home. It’s disgusting, distressing and completely avoidable.

“The sewers serve an important purpose - they are not an abyss for household rubbish. They were only designed to carry water, toilet tissue and human waste. Anything else will block them.

“Cleaning pots and pans with washing up liquid simply does not breakdown cooking fat and oil for good. It goes down the drain easily enough, but when it hits the cold sewers, it hardens into disgusting ‘fatbergs’ that cling to wet wipes and cause blockages in pipes.”

Thames Water is also writing to customers in the worst affected streets and providing them with free ‘fat traps’ to collect used cooking oil.