What is the Water Table?
1 November 2025
Is a Drain Survey Worth It When Buying a House?
1 July 2026
Drainage Advice
Why Does My Drain Keep Blocking in the Same Place?
If you have found yourself asking “why does my drain keep blocking?”, particularly when the problem occurs in the same place every time, there is often an underlying reason that needs investigating. Clearing a blocked drain should normally restore the flow of wastewater, but if the same blockage returns a few weeks or months later, simply clearing it again may only be treating the symptom.
If your drain keeps blocking in the same place, the blockage itself may only be a symptom. Common underlying causes include damaged or displaced pipework, tree root ingress, poor pipe gradients, scale or fat build-up, and foreign objects trapped within the drainage system. Repeated blockages often warrant a CCTV drain survey to establish exactly what is happening underground.
An occasional blocked drain can happen for all sorts of reasons. Too much paper, cooking fats, wipes, hair and other debris can gradually restrict the flow through a pipe until it eventually becomes blocked.
If the drain is cleared properly and doesn’t cause any further trouble, there may be little reason for concern. However, a drain that repeatedly blocks in exactly the same area is different. In these circumstances, continually clearing the blockage can deal with the immediate problem without addressing what is causing it.
Table of Contents
Signs There May Be an Underlying Drainage Problem
- The same drain has blocked more than once.
- Water begins draining slowly again soon after the drain has been cleared.
- You regularly hear gurgling noises from toilets, sinks or drains.
- Unpleasant drain smells keep returning.
- Wastewater or sewage backs up during normal use.
- Several fixtures are draining slowly at the same time.
- You have noticed unusually wet ground, subsidence or movement around the drainage route.
Why Does My Drain Keep Blocking? 6 Common Causes
There isn’t one single reason why a drain repeatedly becomes blocked. The problem could be as simple as material repeatedly being put into the drainage system that should not be there, or it could indicate a structural defect within the underground pipework.
Understanding why your drain keeps blocking is important because the correct solution will depend on what is actually happening inside the drain.
1. Build-Up Inside the Pipe
Fat, grease, soap residue, scale and other debris can gradually accumulate on the internal walls of a drain. Clearing the central obstruction may restore the flow, but significant deposits left behind can allow another blockage to form.
2. Tree Root Ingress
Tree and plant roots naturally seek moisture. If there is a crack or weakness in an underground pipe or joint, fine roots can enter the drainage system and continue growing inside it, catching waste and restricting the flow.
3. Cracked or Damaged Pipework
A damaged section of drain may create an uneven internal surface where paper, waste and debris repeatedly become caught. The blockage can be removed while the defect that caused it remains.
4. Displaced Pipe Joints
Sections of underground pipework can move over time. A displaced joint can create a lip or restriction inside the pipe, making it much easier for passing waste to snag and form another obstruction.
5. Poor Drainage Fall
Wastewater relies on gravity to move through many drainage systems. If a pipe has insufficient gradient, has dropped or developed a low point, solids can settle rather than being carried away effectively.
6. A Foreign Object
Wipes, sanitary products, building debris and other objects can become lodged within pipework. Even if water can still pass around the obstruction, the object may continually catch additional waste until another blockage develops.
Why Does My Drain Keep Blocking After It Has Been Cleared?
If a drain blocks again soon after it has been cleared, there may still be an underlying restriction or defect within the pipework. In some cases, the immediate obstruction is removed successfully but deposits, roots or structural damage remain.
This is why recurring blockages should be looked at differently from a one-off problem. The aim is not only to restore the flow, but to understand why the obstruction keeps returning.
Does Drain Jetting Solve a Recurring Blockage?
High-pressure water jetting is an extremely effective method of removing many drain blockages and cleaning deposits from pipework. In plenty of cases, it is all that is required to restore a drain to proper working order.
The important distinction is whether the blockage is the problem itself or the result of another defect.
If grease, scale or accumulated debris is causing the restriction, thoroughly cleaning the pipe may resolve the issue. If the pipe is cracked, displaced, penetrated by roots or structurally damaged, however, clearing the waste may only provide temporary relief.
Repeatedly Clearing a Drain May Only Treat the Symptom
If a blockage has returned more than once in the same section of drainage, it is worth finding out why. A CCTV drain survey enables the inside of the pipework to be inspected so that structural defects, root ingress, displaced joints and other problems can be identified rather than guessed at.
How Can You Find Out What Is Causing the Blockage?
Underground drainage is largely hidden from view, which means the cause of a recurring blockage cannot always be determined simply by looking at the affected drain or manhole.
This is where CCTV drainage inspection becomes particularly useful. Specialist camera equipment can be passed through the drainage system to provide a view of the internal condition of the pipework.
A survey may reveal problems including root ingress, fractures, displaced joints, scale deposits, obstructions, deformation or sections of pipework that have deteriorated.
KD Drainage provides CCTV drain surveys throughout Kent and the surrounding areas to investigate drainage problems and help determine the most appropriate next step.
What Happens If the Drain Is Damaged?
Finding a damaged drain does not automatically mean that the entire drainage run has to be excavated and replaced.
The appropriate repair will depend on the location, condition and extent of the damage. Modern drainage repair techniques mean that certain defects can be repaired with much less excavation than would traditionally have been required.
Clear the Drain
Any obstruction is cleared so that normal flow can be restored and the drainage system can be properly investigated.
Inspect the Pipework
Where recurring blockages or structural problems are suspected, CCTV equipment can be used to examine the internal condition of the drain.
Identify the Cause
The survey helps establish whether the problem is caused by deposits, roots, damaged pipework, displaced joints or another obstruction.
Recommend the Appropriate Solution
Depending on the defect, options may include further cleaning, root removal, drain relining, localised structural repair or replacement of damaged pipework.
Can a Damaged Drain Be Repaired Without Digging It Up?
In some situations, yes. Drain relining can provide a way of repairing damaged underground pipework from inside the existing drain.
Rather than excavating the entire section of pipe, a new lining is installed within the existing drain to create a new internal surface. Whether this technique is suitable will depend on the nature and severity of the defect.
Smaller isolated defects may also be suitable for localised structural repair or drain patching, allowing a specific damaged area to be repaired without relining a complete drainage run.
Where a pipe is too severely damaged or collapsed for a no-dig solution, excavation and replacement may still be necessary. The important thing is to diagnose the problem first so that unnecessary work is avoided.
Can I Prevent My Drains From Blocking Again?
Not every blockage can be prevented, particularly where underground pipework has developed a structural defect. However, changing what enters the drainage system can significantly reduce the likelihood of avoidable problems.
- Do not pour cooking fats, oils or grease down sinks.
-
Avoid flushing wipes, sanitary products and other non-disposable items. Water UK advises that only the “3 Ps” — pee, poo and toilet paper — should normally be flushed. You can read more on the
Water UK website. - Keep external gullies clear of leaves and surface debris.
- Deal with slow-running drains before they become completely blocked.
- Have recurring problems investigated rather than continually treating them as isolated blockages.
If a drain continues to block despite sensible use, that is a good indication that the drainage system itself may need closer inspection.
Frequently Asked Questions
Why does my drain keep blocking after being cleared?
A drain can block again if deposits remain inside the pipe or if an underlying issue such as root ingress, displaced joints, damaged pipework or poor drainage fall is continually causing waste to collect in the same area.
How many times should a drain block before I get it surveyed?
There is no fixed number. However, if the same drain blocks repeatedly, particularly within a relatively short period, investigating the underlying cause can be more useful than repeatedly clearing it without knowing why the problem is returning.
How do you know if a drain has collapsed?
Recurring blockages, slow drainage, sewage backing up and ground movement can all indicate a problem, but these symptoms do not prove that a pipe has collapsed. A CCTV drain survey can be used to inspect the condition of the underground pipework.
Can tree roots cause a drain to keep blocking?
Yes. Roots can enter drains through cracks, damaged joints or other weaknesses. Once inside, they can grow and catch paper and waste, causing repeated restrictions and blockages.
Will drain relining stop recurring blockages?
If recurring blockages are being caused by a defect that is suitable for relining, repairing the internal pipe surface can address the underlying structural problem. A survey is normally required first to establish whether relining is appropriate.
Do I need a CCTV survey for every blocked drain?
No. Many straightforward blockages can be successfully cleared without a survey. CCTV inspection becomes particularly useful when problems repeatedly return, there are signs of structural damage, or the cause cannot otherwise be established.
Does Your Drain Keep Blocking?
If you keep asking yourself “why does my drain keep blocking?”, KD Drainage can help investigate the underlying cause as well as deal with the immediate obstruction. Our experienced drainage team works throughout Kent and the surrounding areas.
