Blocked Drains: Common Causes and When to Call a Plumber

Blocked drains rarely happen overnight. They build up over weeks or months until the water stops going down. Spotting the early signs and knowing the common causes helps you avoid the messier version of the problem.

Common causes

• Fat, oil and food scraps poured down the kitchen sink
• Hair and soap build-up in showers and basins
• Wipes, sanitary products and paper towel flushed down the toilet
• Tree roots finding their way into underground pipes
• Old or damaged pipes that have shifted or cracked

Early warning signs

• Water draining slowly from sinks, showers or baths
• Gurgling sounds from drains or the toilet
• Bad smells coming from plugholes
• Water pooling around an outdoor drain or gully

What's reasonable to try yourself

For a single slow basin or shower, removing and cleaning the plug or strainer, or using a plunger, often solves it. Be cautious with harsh chemical drain cleaners — they can damage pipes and are dangerous if a plumber later has to work on the same drain.

When to call a plumber

• More than one fixture is blocked at the same time
• Water is coming back up through a drain or toilet
• There's sewage smell or overflow outside
• The blockage keeps coming back

Plumbers can use drain cameras to see exactly what's causing the blockage and high-pressure water jetting to clear it. Ask for the camera footage — it shows whether you're dealing with a one-off blockage or a damaged pipe.