PEOPLE are being asked not to pour cooking fat down the sink but to use it to help feed birds during the winter months.

In a bid to stop sewers getting clogged up with kitchen grease, Thames Water is encouraging its customers in Waltham Forest to mix Sunday roast drippings with seeds, dried fruits or other food scraps.

When cooled the mixture should be hung out in the garden, providing nourishment for birds struggling to survive the plunging temperatures.

The only fats to avoid giving to the birds are lighter polyunsaturated fats like vegetable oil.

Hot fat poured down the plughole quickly solidifies and increases the risk of blockages in the sewer network. This can lead to untreated sewage flooding properties and polluting the environment.

Dr Peter Spillett, head of environment and sustainability at Thames Water, said: "By following our advice, customers can give birds a real helping hand in their battle to survive the cold spell.

"At the same time they will also be helping us protect the environment by reducing the potential for sewer blockages.

"Fat poured down the drain can be a recipe for disaster. It needlessly risks pollution to rivers and streams and also increases the chances of customers' own pipes becoming blocked.

"This can result in their properties, or even their neighbours' properties, being flooded with sewage, a costly and very unpleasant experience."

Thames Water estimates that over 1000 tonnes of cooking fat is swilled down its 40,000-mile sewer network each year and, annually, the company spends around £7 million clearing 100,000 blockages from public sewers, around half of which are caused by fat.

Its advice to customers is to pour the liquid cooking fat carefully into an old tin or another sturdy container.

When it has fully cooled and solidified, the fat should be wrapped in newspaper and put in the bin.