If you've been in the habit of tipping all yourleftover liquids down the plughole, you might want to think twice. Plumbing specialists are sounding the alarm about an unlikely culprit behind 'winter drain problems' that tends to worsen atChristmas.

You may be surprised to hear that the culprit behind these blocked sinks is actually a popular condiment usually served with a roast dinner. Whilst you might assume it's cranberry sauce, horseradish or mustard, experts at Plumbworld have actually pinpointed gravy as the festive troublemaker.

"Gravy is full of fats, oils, meat juices and thickeners that cool very quickly once they hit cold pipes," the experts said, according to theExpress. "What pours away as a smooth liquid becomes a sticky, solid layer inside your drainage system, catching food debris and slowly blocking the pipe.

"The problem grows over the Christmas period because families make and use far more gravy than usual. Between Christmas dinner, Boxing Day leftovers and New Year meals, trays full of meat juices and sauce often end up being rinsed into the sink.

"Each time this happens, another layer of grease sticks to the inside of the pipe. In winter, when outdoor and under-sink pipes are much colder, this fat sets almost instantly. Even a small amount adds to the build-up, and once the pipe is coated, bits of food, vegetables and stuffing cling to it easily, creating the start of a stubborn winter blockage."

Apparently, plumbers have even dubbed gravy 'pipe glue' due to its notorious tendency to stick stubbornly to the inside of pipes. This problematic mixture of fat, starch and food particles doesn't merely wreak havoc on your drainage system – it can also generate some rather foul smells around your home.

The experts continued: "Early signs of a gravy-related blockage include a sink that drains more slowly than usual, gurgling noises, bubbling in the plughole or a sour, greasy smell coming from the drain. If these warnings are ignored, the problem can turn into standing water that won’t drain at all, overflowing outdoor drains or leaks where pressure has built up inside the pipework."

The recommended solution is to handle gravy in the same manner as cooking oil – avoid pouring it down the drain entirely. Instead, allow the remaining sauce to cool down and solidify before disposing of it in the rubbish bin.

This was similarly echoed by Thames Water in its 2025 festive advice. Recent research from the firm claimed that pouring fats, oils, and grease down the kitchen sink is one of the leading causes of blockage-related internal flooding.

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Thames Water is said to tackle up to 75,000 blockages each year, racking up costs of around £40 million. Tess Fayers, Director of Wastewater and Bioresources at Thames Water, said recently: "Our research shows that everyday habits like rinsing leftover food, oil and fatty liquids down the sink or flushing wipes can unintentionally lead to blocked pipes.

"These issues are especially common during the festive season, when cooking and hosting are in full swing. The last thing we want is for the festive season to be ruined by blocked drains. There are some simple changes we can all make to help protect our homes and keep sewers flowing.

"Always scrape fats and oils into the bin before washing up, avoid pouring drinks like hot chocolate or tea down the drain, and avoid flushing anything that isn’t pee, poo or toilet paper, even if the packaging says otherwise.

"These small steps can make a significant difference to our environment and help protect homes for everyone; not just for the festive season but for years to come."