Million of litres of fat will be poured down drains across East Anglia on Christmas Day and emergency crews are on stand by to clear blockages.
Anglian Water is advising customers to dispose of unwanted fats in other ways.
Spokesperson Rachel Thompson said: "Once in the drain where temperatures are much lower the fat solidifies.
"There's a danger of drains becoming blocked. Anglian Water are urging people to poor the fat into containers first before throwing it in the bin."
Feed for birds
There is also an alternative to throwing the residue of the fat away.
Ms Thompson said: "People can put it in a unwanted container and allow it to solidify and put it out for garden birds to feed on.
"Blocked drains can also sometimes cause flooding of properties and other damage which could cost thousands of pounds to put right.
"Householders may be liable to pay for repairs to damaged drains."