You’ve probably seen the news stories: a solid mass of fat, wipes and waste, sometimes weighing many tonnes, pulled out of a sewer beneath a UK city. These are fatbergs, and while the biggest examples make headlines, smaller versions form in ordinary residential and commercial drains all the time.
How a fatberg actually forms
A fatberg starts small. Cooking fat, oil and grease poured down a sink cool and solidify as they travel through the pipe. On their own, they’d eventually wash through, but they rarely travel alone. Wipes, sanitary products, cotton buds and other non-flushable items get caught in the congealing fat, and the mass grows layer by layer every time more fat and waste passes through.
Over time, and especially in a section of sewer with several properties feeding into it, this buildup can grow large enough to block the pipe completely, causing backups, overflows and, in serious cases, sewage escaping into streets or properties.
What contributes to a fatberg
- Cooking fat, oil and grease poured down sinks
- Wet wipes, even ones labelled “flushable”
- Sanitary products and cotton buds
- Nappies and other non-biodegradable waste flushed instead of binned
Why it’s a cumulative problem
It’s tempting to think a small amount of fat or the odd wipe won’t matter, but fatbergs are built up by thousands of households doing exactly that over months and years. Once congealed fat has hardened inside a pipe, it’s dense and sticky, which is why it tends to need mechanical clearance rather than shifting on its own.
Preventing it at home
Let fat cool and scrape it into the bin rather than down the sink, use a sink strainer to catch food scraps, and bin wipes and sanitary products instead of flushing them. Our page on blocked drains covers the other common causes worth knowing about.
If you suspect a fat-related blockage building up in your own drain, call us on 0333 200 1623 before it turns into a bigger job.