Why Drains Keep Blocking After They Are Cleared
If a drain keeps blocking weeks after it was cleared, the first clean restored flow without fixing the cause — and the cause is usually still in the pipe.
In this guide
Fast answer
A drain that keeps blocking almost always has an unfixed cause: tree roots growing back through a cracked joint, grease and fat lining the pipe, a sag or belly that traps water, broken or crushed clay, or wipes catching on a snagged section. Clearing alone restores flow but leaves the problem in place. A CCTV inspection is the quickest way to find and prove what is actually happening before you spend on another clear.
Why a cleared drain blocks again
A blocked drain has two parts — the symptom (no flow) and the cause (what stopped it). An electric eel or a quick jet can punch through the blockage and get water moving again, which feels like the job is done. But if the underlying cause is still there, it simply rebuilds. Tree roots regrow within months. Grease cools and re-lines the pipe wall. A low section of pipe keeps collecting silt and paper because water sits instead of flushing through. If you find yourself calling someone out every few months, you are paying to clear the same blockage repeatedly without ever addressing why it forms. That is the pattern worth breaking — and it is exactly why we diagnose and prove the cause before clearing, rather than clearing blind and hoping it holds. A standard drain clear runs $250–$390, so repeat visits add up fast.
The four causes behind most repeat blockages
Four problems account for the bulk of recurring blockages in Sydney. Tree roots are the most common, especially in older suburbs with clay sewer pipes — fine roots enter through cracks and joints chasing moisture, then catch paper and grease until the line chokes. Grease and fat build up in kitchen lines, narrowing the pipe over time. Sags or 'bellies' — sections where the pipe has dropped out of true fall, often from ground movement or poor bedding — trap water and debris that never fully clears. Damaged pipe, including cracked clay, crushed sections, or displaced joints, both restricts flow and gives roots a way in. Foreign objects and wipes can snag on any of these and finish the blockage off. Most repeat blockages are a combination — roots at a broken joint, or grease settling in a sag.
How CCTV finds and proves the real cause
You cannot fix what you cannot see, and guessing is how people end up paying for the same clear twice. A CCTV drain inspection ($250–$450) sends a camera down the line so you can watch exactly what is happening — where the roots enter, how far the grease extends, whether the pipe sags, and whether a joint is cracked or a section collapsed. Often a quick clear first lets the camera travel the full length. The footage gives you proof, not opinion: you see the metre mark and the defect, so you know whether the next step is hydro jetting ($300–$550) to properly scour grease and roots, a targeted repair, or relining (quoted after CCTV) to seal a damaged section without digging up the yard. It also rules out paying for relining when a clean would do.
When to stop clearing and start fixing
One blockage is bad luck. A second blockage in the same drain is a message: clearing alone is not solving it. That is the point to get eyes on the pipe rather than booking another clear. Call sooner if you also notice gurgling toilets or sinks, slow drainage across multiple fixtures, sewage smells in the yard, or water pooling over the same patch of ground — these point to a structural issue, not a one-off. Recurring blockages near established trees usually mean roots and a damaged joint working together. We are an owner-led, licensed NSW drain trade (Scott Johnstone, licence 1-LCV-265) covering all of Sydney, 24/7, and we work to a simple method — find it, prove it, fix it — so you are not paying to clear the same drain on repeat. If your drain has blocked more than once, get it inspected before the next clear.
Talk to a Sydney drain specialist
If a drain is blocked now, Scott can diagnose the cause on camera and clear it — across all of Sydney, 24 hours a day.
Request drain helpCommon questions
Why does my drain keep blocking even after a plumber cleared it?
Because clearing restores flow but does not remove the cause. Roots, grease, a sag in the pipe, or a cracked joint are usually still there and rebuild the blockage over weeks or months. A CCTV inspection shows which one it is so it can be properly fixed.
Does a repeat blockage always mean a broken pipe?
No. Grease, wipes, silt, and tree roots can all return without the pipe being broken. That said, recurring blockages near trees often involve roots entering through a cracked joint. A camera inspection confirms whether the pipe itself is damaged or just needs a deeper clean.
Is it worth paying for a CCTV inspection?
If a drain has blocked twice, yes. A CCTV inspection ($250–$450) shows and proves the exact cause, so you stop paying for repeat clears at $250–$390 each and spend once on the right fix — whether that is hydro jetting, a repair, or relining.
