If your drains keep blocking, there’s usually a reason for it.

A one-off blockage is fairly normal. But if it keeps happening, something is either staying in the pipe or the pipe isn’t letting waste flow away properly.

Clearing it each time might solve it temporarily, but it won’t stop it coming back.

What’s Actually Happening

When a drain blocks, it’s because something is restricting the inside of the pipe.

Even if it clears, part of that restriction often stays there. That narrowed section then catches more debris the next time water flows through.

That’s why repeat blockages tend to come back — and often get worse over time.

The Most Common Causes

Grease and Fat (Kitchen Sinks)

This is one of the biggest causes of repeat blockages.

Grease goes down the sink as a liquid, but it cools and sticks to the inside of the pipe. Over time it builds up into a thick layer.

Once that’s there, it starts catching food waste and debris, and the pipe gradually narrows.

Hair and Soap Build-Up (Bathrooms)

In showers and bathroom sinks, the usual issue is hair mixed with soap residue.

This forms a dense build-up that sticks inside the pipework. It often doesn’t fully clear, even if the water starts draining again.

Pipework That Doesn’t Flow Properly

If the pipe doesn’t have enough fall (slope), waste won’t move through it properly.

Instead, it slows down and settles, which makes it much easier for build-up to form.

In some cases, the pipework has simply been poorly installed, which is something that does come up more often than you might expect.

Where that’s the case, the drain might keep blocking no matter how many times it’s cleared.

Tree Roots (External Drains)

Tree roots can get into drainage pipes through very small gaps or joints.

Once inside, they grow towards the moisture and start to restrict the pipe.

This isn’t always obvious straight away, but it often leads to repeated blockages that don’t fully clear.

What You Can Try

If the blockage is near the surface, you might be able to clear it with:

• a plunger

• removing and cleaning the trap

• flushing through with hot water

This can work for minor or early blockages.

But if the problem keeps coming back, it’s usually because the pipe hasn’t been properly cleared.

When It’s Not a Quick Fix

If your drains are blocking repeatedly, it’s usually a sign that something is still sitting in the pipe or the system isn’t draining properly.

At that point, it’s less about clearing it again and more about finding the cause.

In many cases, the pipe needs to be properly cleaned using high-pressure water jetting, which clears out built-up grease, debris, and residue along the pipe walls — not just the blockage itself.

If the issue isn’t obvious, a CCTV drain inspection can be used to see exactly what’s going on inside the pipe, whether that’s build-up, a partial blockage, or an issue with the pipework.

Otherwise, it tends to become a cycle of blocking, clearing, and blocking again.

Final Thoughts

Drains don’t usually block repeatedly without a cause.

Most of the time it’s build-up that’s been there for a while, or something in the pipe that hasn’t been fully removed.

Sorting it properly early on usually saves dealing with the same issue over and over again.