Tree Roots in Your Sewer Pipes: Causes, Signs and Fixes

Tree root intrusion is one of the most common causes of recurring sewer blockages in Sydney, especially in older, leafier suburbs with mature street trees and established gardens. Left alone, roots inside a sewer line get worse over time and can eventually collapse the pipe.

Why roots grow into sewer pipes

Tree roots are naturally drawn to the moisture and nutrients inside sewer pipes. Older terracotta and clay pipes, common in homes built before the 1970s, are joined in short sections, and those joints are where roots first find their way in. Even a hairline crack or a slightly misaligned joint is enough for fine root hairs to penetrate, after which they thicken and expand inside the pipe.

Trees to watch around Sydney

Some species are far more aggressive with roots than others. Large eucalypts and gum trees, fig trees, willow trees and paperbarks are among the worst offenders, and their roots can travel well beyond the tree's canopy in search of water. A tree on the street outside your property can be just as much of a risk as one in your own backyard.

Signs of root intrusion

• Drains that block repeatedly, often within weeks of being cleared
• Gurgling sounds from drains or toilets when water runs elsewhere
• Slow-draining sinks, showers and toilets across multiple fixtures
• A sewage smell around external drains or inside the home
• Unusually lush or soggy patches in the yard above the sewer line

Diagnosis and repair options

The most reliable way to confirm root intrusion is a CCTV drain inspection, which shows exactly where roots have entered and how much damage they've caused. From there, options range from high-pressure jetting to clear the roots (a temporary fix if the pipe is cracked), to cutting the roots back, to pipe relining (inserting a new lining inside the existing pipe), to excavating and replacing the damaged section for severe collapse.

Prevention

Avoid planting large, thirsty trees close to sewer lines, and if you're buying an older home, a pre-purchase CCTV inspection can reveal whether the sewer line is in good condition before it becomes your problem. Regular maintenance clears roots before they grow large enough to collapse the pipe.