Most blocked drains come down to a fairly short list of repeat offenders. Knowing what they are, and why some of them keep causing the same drain to block again and again, makes it much easier to avoid a repeat call-out.
1. Fat, oil and grease
Poured down a sink while warm, fat and grease cool and solidify inside the pipe, narrowing it a little more each time. This is one of the most common causes of a drain that blocks repeatedly rather than just once.
2. Wet wipes
Even wipes labelled “flushable” don’t break down the way toilet paper does. They catch on any rough edge inside the pipe and build up over time, often combining with fat to form a much larger blockage.
3. Hair
Hair binds with soap scum and grease to form a dense clump, most often in bathroom sinks and shower drains. A small amount clears easily, but left unchecked it becomes one of the most persistent blockages to shift.
4. Food waste
Coffee grounds, rice, pasta and vegetable peelings are common kitchen sink culprits. Some of these expand or turn starchy when wet, which is exactly the wrong property for something travelling through a pipe.
5. Sanitary products and cotton buds
Like wipes, these don’t disintegrate. They’re a frequent cause of blockages in bathroom waste pipes and, further downstream, in the wider sewer network.
6. Tree root ingress
Roots don’t force their way into a healthy pipe. They exploit an existing weak joint or crack, then keep growing and catching debris every time water passes, which is why root-related blockages tend to come back at the same spot.
7. A partial pipe collapse or displaced joint
A section of pipe that’s sagged, cracked or shifted creates a ledge or dip where debris naturally settles. Clearing the debris without fixing the underlying fault means the same spot will block again within weeks or months.
8. Scale build-up
Mineral deposits from hard water gradually narrow a pipe’s internal diameter over years. On their own they rarely cause a full blockage, but they make it far easier for fat, hair or debris to catch and build up faster than they otherwise would.
9. Leaves and outdoor debris
External gullies and outside drains collect leaves, moss and general garden debris, particularly in autumn. Left to accumulate, this is one of the more preventable causes on this list with a simple, regular clear of the grate.
10. Foreign objects
Toys, nappies, and other items that shouldn’t go down a toilet or sink are a surprisingly common cause of sudden, total blockages, usually needing more than a plunger to shift.
Why some of these keep coming back
Fat, hair and wipes are largely down to habits, and are usually solved by changing what goes down the sink or toilet. Root ingress, pipe collapses and scale are different. These are structural, which means clearing the visible blockage doesn’t fix the cause, and the same spot will likely block again. If a drain has blocked more than once in the same place, that’s the signal worth acting on.
Getting to the real cause
A CCTV drain survey shows exactly what’s happening inside the pipe, so you’re not left guessing after each clear-out. If the survey finds a structural issue, our drain relining service can usually fix it without digging up the garden or driveway.
If a drain at your property keeps blocking, call us on 0333 200 1623 and we’ll find out which of these is actually behind it.