Fat Bergs and Blocked Drains: How to Prevent Them in Your Home
Fat, oil and grease — known in the drainage industry as FOG — are the number one cause of blocked drains in UK homes. Every year, water companies across Britain deal with around 300,000 sewer blockages, and the majority involve fat deposits. Here's how to keep your {location} drains clear.
How Fat Blocks Your Drains
When you pour cooking oil, fat or grease down the sink, it's liquid and seems harmless. But as it travels through your pipes and cools, it solidifies. It sticks to the pipe walls and builds up layer by layer. Over time, it combines with other waste — wet wipes, food scraps, soap residue — to form solid blockages.
In the public sewer network, these accumulations become the infamous fatbergs that make national news. But the problem starts in your own pipes. A domestic fat blockage typically occurs in the first few metres of pipework between your kitchen sink and the manhole or inspection chamber.
What Should Never Go Down the Drain
- Cooking oil and fat — including olive oil, vegetable oil, butter, lard and coconut oil
- Meat juices and gravy — these contain high levels of animal fat
- Food scraps — even small particles build up over time
- Wet wipes — including those labelled "flushable" (they don't break down like toilet paper)
- Coffee grounds — they clump together and stick to fat deposits
- Sauce and condiments — mayonnaise and salad dressings are particularly fatty
5 Habits That Keep Your Drains Clear
- Scrape plates into the bin — before washing up, scrape all food waste into your general waste or food recycling bin
- Collect cooking fat in a container — let it cool and solidify, then dispose of it in the bin. Many councils in {location} accept cooking oil at recycling centres
- Use a sink strainer — a simple mesh strainer over the plughole catches food particles before they enter the drain. They cost less than £3 and prevent most kitchen blockages
- Run hot water after washing up — a blast of hot water with a squirt of washing-up liquid helps keep the immediate pipework clear
- Monthly maintenance flush — pour a kettle of boiling water mixed with a tablespoon of biological washing powder down the kitchen sink once a month. The enzymes help break down grease deposits in the trap and initial pipe run
Signs of a Building Fat Blockage
Catch it early by watching for:
- Water draining more slowly than usual from the kitchen sink
- Gurgling sounds from the plughole after the water drains
- Unpleasant smells from the sink, particularly in warm weather
- Water backing up into the sink when the washing machine drains
What to Do If You Have a Fat Blockage
For a minor blockage in the kitchen trap, try a drain unblocker product containing enzymes (avoid caustic soda on plastic pipes). For anything beyond the trap, you need professional help. A drainage engineer in {location} can clear fat blockages using high-pressure water jetting, which scours the pipe walls clean.
If blockages keep recurring, ask for a CCTV survey. There may be a structural defect — a dipped section of pipe where fat accumulates, or a displaced joint catching debris. A NADC-registered contractor can diagnose the cause and recommend a permanent fix.
Prevention is far simpler and cheaper than clearing a blocked drain. Change your kitchen habits today and your drains will thank you for years to come.