If you’re accustomed to pouring all your liquids down the sink, it might be time for a rethink. Plumbing experts are warning Brits about an unexpected cause of ‘winter drain problems’ that often intensifies over the festive period.
The culprit causing these sink blockages is not what you might expect – it’s a common condiment usually served with a roast dinner. While cranberry sauce, horseradish or mustard may spring to mind, Plumbworld specialists have identified gravy as the main Christmas offender.
“Gravy is full of fats, oils, meat juices and thickeners that cool very quickly once they hit cold pipes,” the experts said. “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.”
Plumbing professionals have even dubbed gravy ‘pipe glue’ owing to its notorious ability to cling stubbornly to pipe interiors. The troublesome concoction of fat, starch and food remnants doesn’t just create chaos in your drainage system – it can also produce rather unpleasant odours throughout your property.
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.
Thames Water also reportedly clears up to 75,000 blockages annually, costing as much as £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.”
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