It's not just beer you need to be thinking about16:16, 30 Jun 2026While most of us know not to pour cooking oil or melted cheese down the drain because it can cause stubborn blockages and expensive plumbing bills, there's another surprising culprit many people overlook.‌Experts at Which? notes that beer could cause issues. Yes, that crisp, refreshing alcoholic drink many had at the pub during the heatwave.‌While pouring beer down the sink isn't as harmful as tipping oil down the drain, experts say doing it regularly could still cause problems over time. The consumer champions explain: "Pouring beer down the sink occasionally and in small amounts is generally harmless.‌"However, avoid disposing of large quantities regularly. This could lead to potential issues like clogging or bad odours over time, because beer contains sugars, yeast, and other organic matter that can build up."Don't pour cream liqueur down the sinkThat's not the only alcoholic drink that can cause issues. It's bad news if you like cream liqueurs. Experts at SAGE note: "Cream liqueurs have enjoyed a resurgence in popularity in recent years. These creamy alcoholic drinks are flavoured with everything from mango and strawberry to espresso and salted caramel."However, whatever the flavouring, they are all classed as FOG and can wreak havoc on pipes."‌SAGE notes that FOG stands for fats, oils and grease. Said to be a "plumber's worst nightmare" this also includes gravy, ice cream, cream, cooking oils, salad dressings, butter and lard.Don't pour tuna liquid down the sinkIt's not just drinks you need to worry about; even tuna could cause issues. On Friday (June 26), BBC DIY SOS presenter Nick Knowles appeared on Morning Live to discuss fatbergs.‌He urged people not to pour tuna brine or oil down the sink. Although tuna brine is mostly water and salt, leftover fish oils and food particles can build-up in pipes, combine with grease and soap, and eventually cause stubborn blockages or fatbergs.He said: "Don't pour your oils down the sink. I mean, most people know not to pour oils down your sink in the bathroom or in your kitchen now."But actually, most of us will drain a tin of tuna into the sink. With the oil that's in a tin of tuna, or maybe the fat from an air fryer, or coffee grounds, all these things, add to create a block."Article continues belowInstead, Nick advises scraping it into a disposable container. "Like a baked bean tin or anything else that you're throwing, and put them in the bin and get rid of them that way", he said.What are the signs my sink is blocked?Spencer Darley of Which? Trusted Trader company Drain Jet Yorkshire, says there are three key signs your drain might be getting clogged:Smells: In the early stages of a drain blockage, you might notice unpleasant odours resembling rotten food, stale or musty smells or sewage-like odours. These smells occur because trapped debris begins to decompose or stagnant water allows bacteria to grow.A glugging sound: A glugging sound from your drain usually indicates air is trapped in the pipes and struggling to escape as water flows past. ‘The glugging is the sound of the airflow getting more and more restricted,’ Spencer says.The water drains more slowly: If the issue is not tackled, water may eventually stop flowing altogether.