Why does my drain keep blocking?

The one thing every recurring blockage has in common is that a one-off clearance keeps the pipe running for a while, then the same drain backs up again a few weeks or months later. That's not bad luck — it's the underlying cause reasserting itself. Whatever caused the first blockage is still there, still catching the same debris, still narrowing the pipe. Clearing the material that built up on it doesn't fix it.

The useful question isn't 'how do I clear it again' — it's 'what's the pipe doing that keeps catching stuff'. There are five common answers, and the signs are usually specific enough to tell them apart before we even get a camera down.

The single most common cause we see on Northamptonshire properties built before the 1970s. Clay pipe joints are sealed with mortar that eventually cracks; small roots find the crack, work their way in, and once inside grow into fine fibrous masses that catch every bit of tissue, hair and grease going past. Clear the pipe and the roots are still there — the mass just re-grows and the same blockage returns three months later.

Signs it's roots: recurring blockages every few months in the same section, worst in spring and autumn when trees are actively growing, and often a smell of decay because organic material is sitting caught in the mass. A large tree within 10 metres of the drain run — especially poplar, willow or ash — makes it much more likely.

Fat that goes down a warm kitchen sink is liquid. Fat that reaches a cold external drain 5 metres later isn't — it hardens on the pipe wall, and every subsequent wash adds another layer. Over months, the effective diameter of the pipe shrinks until it can't cope. Standard clearance punches a hole through the softest bit, water flows again, but the pipe wall coating is still there and it re-narrows quickly.

Signs it's fat: kitchen-side blockages that recur, worse after big cook-ups or in cold weather when the pipe contents are coldest, and a coating you can see if you shine a torch down the gully. Restaurant, takeaway and food-business drains are almost always this. The fix is jetting rather than rodding — high-pressure water strips the full pipe wall clean, not just a channel through the middle.

Ground movement, subsidence and heavy traffic overhead all shift pipes slightly over time. Once a joint has moved even a few millimetres out of line, there's a lip where waste catches on its way past. Tissue and grease build up on that lip and blockages start forming there repeatedly — because the physical shape of the pipe now traps material every time water flows past.

Signs of misalignment: blockages always form in the same spot (often visible on a survey as material building up at the same joint each time), sometimes on a run near a driveway or road, sometimes on clay soil that expands and contracts with the seasons. Only a CCTV survey can confirm it — from the surface it looks identical to a fat or root problem, but the fix is different: a patch repair or a section reline, not more clearing.

In hard-water areas, limescale can form deposits inside the pipe over years. In older drains near roads or unmade driveways, silt washes in through gully covers and settles at low points. Neither one blocks a pipe on its own, but both progressively narrow the diameter until normal use starts to back up. The signature here is drains that get gradually slower rather than blocking suddenly — a slow decline over months, not a one-off event.

Jetting clears it, but if it's happening across the whole system you'll want to look at where the silt is entering (usually a broken gully cover or a downpipe washing straight into the drain) so it doesn't just re-accumulate.

The most serious of the five. When part of a pipe has cracked open, broken, or the top has crushed inward, waste has to force its way past a physical obstruction every time. It'll flow for a while, catch on the broken edge, back up. Clear it, run for a few weeks, back up again.

Signs of collapse: blockages return quickly (weeks not months), sometimes with visible soil or grit coming through the drain, and often surface signs above — a soft patch of lawn, a dip in a driveway, water pooling above where the pipe runs. This is not one to keep clearing. It won't fix itself, and repeated pressure clearances against a collapsed section can push more of the surrounding soil into the pipe and make the eventual repair bigger.

Every recurring blockage we go to starts the same way: clear the immediate problem so we've got a working pipe, then put a CCTV camera down it. The camera goes to where the blockage was forming and looks at the pipe wall itself. Roots are unmistakable — you see the mass. Fat is a smooth cream coating on the pipe wall. Misalignment is a visible step at a joint. Scale and silt show as narrowing and low-point build-up. A collapse is a break, a dip, or daylight where there shouldn't be any.

Once we've seen it, the fix follows: jetting for fat, roots or scale where the pipe is otherwise sound; a patch repair for a single displaced joint or short crack; a full-length lining if the pipe is failing along its whole length. We show you the footage before quoting so you can see for yourself why we're recommending one approach and not another. Our first-hour visit is a fixed £300 and includes the CCTV check where needed — no separate camera fee tacked on afterwards.