People are being warned not to pour the hot grease and fat from the Christmas turkey down the sink.
Irish Water and Clean Coasts are launching a new "Think Before You Pour" campaign, aimed at reducing the number of sewer blockages and overflows.
They're calling for people to stop using the sink like a bin.
A survey as part of the campaign shows six in ten people pour their unwanted fats, oils and greases down the sink.
Congealed fat and other 'non-flushable' products such as baby wipes can create so-called 'fatbergs' in sewer systems.
Officials say almost 8,000 blockages have been cleared so far this year.
Tom Cuddy from Irish Water explained that the blockages can cause big problems.
He said: "We have a lot of examples of fatbergs that have taken us days and even up to a week to clear.
"Some of them could be 10 metres or so in length, and there could be a couple of tonnes of material in them.
"It's not just the fat that's in them: they're gluing together a lot of wipes and debris like that that's flushed down the toilet."
He added: "From a good turkey you'll probably get around a litre of grease and fat.
"That looks nice and liquid when it's coming off the pan, but if you let it sit in a bowl for a while you'll see what it looks like when it gets into the drain."
He said people should instead put the fat aside, let it cool, put it in a container and then dispose of it in the bin.