Festive chefs are being urged to avoid the temptation of pouring Christmas cooking fat down the sink.
Cooking fat down the drain is a 'recipe for disaster'
MPs are being briefed by Thames Water to pass on the message that fat poured down plugholes risks blocking the sewerage network.
Thames Water estimates that the annual yuletide feast of turkey, goose, beef, and ham leads to a 25% increase in the amount of fat ending up down the drain.
Cooks are urged to wrap solidified fat in newspaper and put it in the bin.
Labour MP Howard Stoate prompted the festive alert in a Commons motion which warned that fat-blocked drains can lead to untreated sewage flooding homes and polluting the environment.
"Everyone has a role to play in protecting the environment and their own pockets, by doing all they can to stop fat blocking sewers," the Dartford MP said.
"It is a particularly important message over the festive season, when chefs everywhere are working doubly hard to cater for Christmas parties."
Thames Water, which manages more than 40,000 miles of sewer system, has to clear fat blockages from around 2% of the network - over 800 miles of sewer, or further than from London to Madrid.
The company spends around £7m every year clearing 100,000 blockages from public sewers - about half of which are caused by fat.
Soho in central London is one of the worst effected areas. Once, Thames Water flushers had to clear a solid section of fat blocking a whole 150ft length of sewer.
Instead of pouring cooking fat down the sink, householders are being advised to put it into an old tin or other sturdy container.
Once cool and solidified, the fat should be wrapped in newspaper and binned.
However, fat with high nutritional content, such as lamb and beef suet, can be mixed with seeds, food scraps and dried fruit and hung outside for garden birds.
Tony Dearsley, Thames Water's environment manager, said: "Cooking fat poured down the drain can be a recipe for disaster at any time of year - but the risk is much greater at Christmas, the peak time for meat sales.
"A blocked drain is bottom of everybody's Christmas list, as they can cause householders' own properties to flood, a costly and very unpleasant experience."