A drain that blocks once has usually been given something it could not cope with. A drain that blocks again and again has a problem that clearing alone will not fix.
1. The first clearance did not remove everything
Rodding can punch a hole through a blockage without removing it all. Water flows again, but the remaining material narrows the pipe and quickly catches more debris.
Fix: drain jetting cleans the pipe back to its full bore rather than just opening a channel.
2. Build-up along the pipe
Fat, grease, soap and scale gradually coat the inside of the drain. Over time, the pipe effectively gets smaller, and blockages happen more easily.
Fix: jetting to remove the build-up, plus changes to what goes down the sink. See how to prevent blocked drains.
3. Tree roots
Roots enter older drains through cracks and joints. Once inside, they grow into a mesh that catches paper and debris. Cutting or jetting them out gives temporary relief, but they grow back through the same gap.
Fix: a CCTV drain survey to find where roots are entering, then a drain repair to seal the joint or crack.
4. Displaced joints
When pipe sections shift (because of ground movement, tree roots or heavy vehicles), the joint between them develops a lip. Solids catch on that lip every time.
Fix: a repair to realign or reline the affected section.
5. A sag or belly in the pipe
If a section of drain has sunk, water and solids settle in the dip instead of flowing through. It may block regularly at exactly the same point.
Fix: a survey to confirm the sag, then a repair, often by excavating and relaying that section.
6. Cracked or collapsed pipe
A cracked pipe can let soil in and water out. A partly collapsed section restricts flow. Both cause repeated blockages and get worse over time.
Fix: repair or replacement of the damaged section.
7. How the drain is being used
Sometimes the pipe is fine but the use is not. Wipes, sanitary products, fat and food waste will block even a perfect drain. In shared houses, heavy use makes this more likely.
Fix: clear guidance for everyone using the drain, and bins in bathrooms.
8. Poor original design
Some drains were laid with too little fall, too many bends or undersized pipes, often during extensions. They are prone to blockages from the start.
Fix: depends on the layout. A survey helps show what options exist.
How to find the real cause
The quickest route from guesswork to an answer is a camera survey. It shows exactly what is happening inside the drain and where, so any fix deals with the cause rather than the symptom.
If your drain keeps blocking and you are in or near Southampton, see drain unblocking in Southampton, CCTV drain surveys in Southampton and drain repairs in Southampton, or get in touch.