How to Unblock a Badly Blocked Drain

Quick answer: For a badly blocked drain, start with a plunger or drain snake to physically clear debris, followed by a CCTV inspection if the blockage persists or keeps returning. Severe blockages are often caused by tree root intrusion or damaged pipework that DIY methods can't fix. In these cases, calling a professional is the safest and most effective solution.

What Makes a Drain "Badly Blocked"?

Not all blockages are created equal. A badly blocked drain typically shows one or more of these signs:

• Water isn't draining at all, or is draining extremely slowly across multiple fixtures
• The blockage keeps returning even after clearing it
• Water is backing up into other drains, sinks, or the shower when you flush the toilet
• There's a strong, persistent odour that doesn't go away
• You've already tried DIY methods without any lasting success

When a blockage hits this level, it's usually no longer a simple case of hair or food scraps sitting near the surface. More often, it points to a deeper issue, significant grease build-up, tree root intrusion, or even structural pipe damage further down the line.

5 Steps You Can Try Before Calling a Plumber

1. Identify how widespread the blockage is

Check whether just one fixture is affected, or several. If your toilet, shower, and sink are all playing up at once, this points to a blockage in your main line. A job better suited to a professional than a DIY fix.

2. Try a plunger first

For single-fixture blockages, a good plunge is still one of the most effective first steps. Make sure there's enough water in the bowl or sink to create a proper seal, and use firm, steady pumps rather than one hard push.

3. Use a drain snake for deeper blockages

If plunging doesn't shift it, a drain snake can physically reach further into the pipe to hook out hair, debris, or buildup that liquid solutions can't touch.

4. Check external drains and grates

Sometimes a "bad" blockage is actually further along the line, at an external drain or grate that's become clogged with leaves, dirt, or debris. Clearing this can sometimes resolve the issue entirely.

5. Avoid repeated chemical treatments

If you've already tried a chemical drain cleaner without success, resist the urge to keep pouring more down. Beyond being ineffective on severe blockages, repeated chemical use can damage older pipes over time.

If the plunger is not shifting it, how to use a plunger properly covers the technique that gets the best result.

How a Professional Plumber Tackles a Badly Blocked Drain

A qualified plumber approaches a severe blockage very differently to a DIY attempt:

1. CCTV drain camera inspection to see exactly what's happening inside the pipe and pinpoint the exact location and cause of the blockage
2. High-pressure water jetting to clear stubborn build-up, tree roots, and debris that manual methods can't reach
3. Assessment of pipe condition to check for cracks, misalignment, or collapse
4. Tailored repair recommendations, which may include trenchless pipe relining if damage is found

If the inspection reveals actual pipe damage, it doesn't automatically mean your yard needs to be dug up. Trenchless technology means it's often possible to repair broken pipes without excavation, saving significant time, cost, and disruption compared to traditional replacement.

For a closer look at the methods involved, read what plumbers do to unclog drains and how to tell if a clog is deep. You can also see our blocked drains and sinks service page.

Don't Let a Bad Blockage Get Worse

A badly blocked drain is not something you should ignore! Reach out to a licensed and insured team of Melbourne. Go to My Plumbing Services today for a fast, same-day repair, and 24 hours available to all your plumbing needs.