TV presenter Nick Knowles urges public to stop pouring tuna liquid down sinks, preventing fatberg damage.

BBC presenter Nick Knowles is urging people across the UK to stop pouring liquid from tinned tuna down their kitchen sinks. The warning, delivered on BBC Morning Live on June 26, 2026, targets a habit millions of households do without a second thought — and the consequences can be severe Cambridge News.
The oil in tuna tins contributes to fatbergs — giant, concrete-like blockages that clog sewer networks. The UK clears around 300,000 of these blockages every year at a cost of between £100 million and £200 million Leeds Live. Around 3,000 homes flood annually because of them.
Most people know not to pour a pan of chip fat down the sink. But Knowles says the oil lurking in a tuna tin is just as dangerous. "Most of us will drain a tin of tuna into the sink," he said on Morning Live. "With the oil that's in a tin of tuna... it adds to create a block" Cheshire Live.
Once oil enters a drain, it cools and hardens. Over time it combines with other fats and non-biodegradable waste to form fatbergs. Thames Water alone spends £18 million a year clearing 75,000 blockages in its network. Even tuna brine — which is mostly salt water — contains fish oils and protein that build up inside pipes Examiner Live.
The scale of the fatberg problem is staggering. In 2017, a 130-tonne fatberg — equivalent to 11 double-decker buses — was found beneath Whitechapel in East London. A 400-tonne mass was later discovered in Liverpool in 2019. Clearing them requires high-pressure extraction and costs millions in specialist work Daily Post.
When fatbergs block sewers, raw sewage backs up into homes and spills into rivers and waterways. Water UK says 93% of sewer blockages contain wet wipes. United Utilities reports that 90% of all blockages come from fats and so-called "unflushables." Water bills have already risen by 26% in 2025-2026, partly to cover these infrastructure costs Head Topics.
Knowles recommends a simple fix. Let oil or fat cool completely first. Then scrape it into a disposable container — an old jar works well — and put it in the bin. For tuna liquid specifically, soaking it up with kitchen roll and disposing of it in a food waste bin is the safest option Cambridge News.
He also warns against flushing cotton buds, nappies, and wet wipes down the toilet. These items combine with FOG — fats, oils, and grease — to form the solid masses that block sewers. Pouring substances like these into the drain may even be illegal. Under the Water Industry Act 1991, it is a criminal offence to discharge anything into public sewers that blocks the free flow of waste Leeds Live.
Not everyone is convinced. On forums like Mumsnet and Reddit, some users argue it is impractical to collect "tiny amounts" of oil from every tuna tin. They say the focus should be on industrial polluters rather than individual households. A survey from Unblocktober 2025 found that 29% of UK adults say cooking oil is the hardest product to dispose of responsibly Examiner Live.
Meanwhile, a new wave of "no-drain" tuna products has quietly emerged. These tins are cooked once inside the can, keeping natural moisture without added oil or brine. There is nothing to drain — and nothing to dispose of. It is a product innovation that sidesteps the problem entirely, though it remains a niche option for most shoppers Cheshire Live.
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